Here's a short story:

The Bilateria or bilaterians, or triploblasts, are animals with bilateral symmetry, i.e., they have a head ("anterior") and a tail ("posterior") as well as a back ("dorsal") and a belly ("ventral"); therefore they also have a left side and a right side. In contrast, radially symmetrical animals like jellyfish have a topside and a downside, but no identifiable front or back. 

The bilateria are a major group of animals, including the majority of phyla but not sponges, cnidarians, placozoans and ctenophores. For the most part, bilateral embryos are triploblastic, having three germ layers: endoderm, mesoderm, and ectoderm. Nearly all are bilaterally symmetrical, or approximately so; the most notable exception is the echinoderms, which achieve near-radial symmetry as adults, but are bilaterally symmetrical as larvae. 

Except for a few phyla (i.e. flatworms and gnathostomulids), bilaterians have complete digestive tracts with a separate mouth and anus. Some bilaterians lack body cavities (acoelomates, i.e. Platyhelminthes, Gastrotricha and Gnathostomulida), while others display primary body cavities (deriving from the blastocoel, as pseudocoel) or secondary cavities (that appear "de novo", for example the coelom). 

The hypothetical most recent common ancestor of all bilateria is termed the "Urbilaterian". The nature of the first bilaterian is a matter of debate. One side suggests that acoelomates gave rise to the other groups (planuloid-aceloid hypothesis by Graff, Metchnikoff, Hyman, or ), while the other poses that the first bilaterian was a coelomate organism and the main acoelomate phyla (flatworms and gastrotrichs) have lost body cavities secondarily (the Archicoelomata hypothesis and its variations such as the Gastrea by Haeckel or Sedgwick, the Bilaterosgastrea by Gösta Jägersten , or the Trochaea by Nielsen). (End of story)

Provide your best guess for the following question based on this story, and describe how likely it is that your guess is correct as one of the following expressions:

Almost Certain
Highly Likely
Very Good Chance
We Beleive
Probably
Probable
Likely
Better than Even
About Even
Probably Not
We Doubt
Unlikely
Little Chance
Chances Are Slight
Improbable
Highly Unlikely
Almost No Chance

Give ONLY the guess and your confidence, no other words or explanation. For example:

Guess: <most likely guess, as short as possible; not a complete sentence, just the guess!>
Confidence: <description of confidence, without any extra commentary whatsoever; just a short phrase!>

Here are a few examples of questions and answers:

Question: what is this article about?
Guess: The bilateria
Confidence: <appropriate level of confidence in this guess>

Question: are they considered animals?
Guess: Yes
Confidence: <appropriate level of confidence in this guess>

Question: are sponges part of them?
Guess: No
Confidence: <appropriate level of confidence in this guess>

Question: what else are they called?
Guess: bilaterians,
Confidence: <appropriate level of confidence in this guess>

Question: or?
Guess: triploblasts
Confidence: <appropriate level of confidence in this guess>

Question: what is the scientific name for the tail?
Guess: posterior
Confidence: <appropriate level of confidence in this guess>

Question: what about belly?
Guess: ventral
Confidence: <appropriate level of confidence in this guess>

Question: do they have a head?
Guess: Yes
Confidence: <appropriate level of confidence in this guess>

Question: what is the other word for head?
Guess: anterior
Confidence: <appropriate level of confidence in this guess>

Question: do all of them have a separate mouth and anus?
Guess: yes
Confidence: <appropriate level of confidence in this guess>

Question: what has germ layers?
Guess: bilateral embryos
Confidence: <appropriate level of confidence in this guess>

Now answer the following question in the same format.

Question: how many layers?

Three