Here's a short story:

Before the 20th century, the term matter included ordinary matter composed of atoms and excluded other energy phenomena such as light or sound. This concept of matter may be generalized from atoms to include any objects having mass even when at rest, but this is ill-defined because an object's mass can arise from its (possibly massless) constituents' motion and interaction energies. Thus, matter does not have a universal definition, nor is it a fundamental concept in physics today. Matter is also used loosely as a general term for the substance that makes up all observable physical objects. 

All the objects from everyday life that we can bump into, touch or squeeze are composed of atoms. This atomic matter is in turn made up of interacting subatomic particles—usually a nucleus of protons and neutrons, and a cloud of orbiting electrons. Typically, science considers these composite particles matter because they have both rest mass and volume. By contrast, massless particles, such as photons, are not considered matter, because they have neither rest mass nor volume. However, not all particles with rest mass have a classical volume, since fundamental particles such as quarks and leptons (sometimes equated with matter) are considered "point particles" with no effective size or volume. Nevertheless, quarks and leptons together make up "ordinary matter", and their interactions contribute to the effective volume of the composite particles that make up ordinary matter. (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 did the term matter include prior to the 20th century?
Guess: ordinary matter composed of atoms
Confidence: <appropriate level of confidence in this guess>

Question: And excluded?
Guess: other energy phenomena
Confidence: <appropriate level of confidence in this guess>

Question: What does science consider these particles to be?
Guess: massless particles
Confidence: <appropriate level of confidence in this guess>

Question: What is a type of massless particle?
Guess: photons
Confidence: <appropriate level of confidence in this guess>

Question: Is it matter?
Guess: no
Confidence: <appropriate level of confidence in this guess>

Question: What is one example of fundamental particles?
Guess: leptons
Confidence: <appropriate level of confidence in this guess>

Question: What's another?
Guess: quarks
Confidence: <appropriate level of confidence in this guess>

Question: What are they considered?
Guess: they are considered "point particles"
Confidence: <appropriate level of confidence in this guess>

Question: What is the term matter loosely used to refer to?
Guess: composite particles
Confidence: <appropriate level of confidence in this guess>

Now answer the following question in the same format.

Question: What is the effective size of point particles?

no size or volume.