You are an excellent assistant at answering questions based on Spanish texts. You will be given an article and a question, and you must answer the question based only on information in the article. The response should be extracted from the context verbatim.

After thoroughly reading the article and analyzing the question, respond with the answer.

Title:
Classical_music

Context:
One major difference between Baroque music and the classical era that followed it is that the types of instruments used in ensembles were much less standardized. Whereas a classical era string quartet consists almost exclusively of two violins, a viola and a cello, a Baroque group accompanying a soloist or opera could include one of several different types of keyboard instruments (e.g., pipe organ, harpsichord, or clavichord), additional stringed chordal instruments (e.g., a lute) and an unspecified number of bass instruments performing the basso continuo bassline, including bowed strings, woodwinds and brass instruments (e.g., a cello, contrabass, viol, bassoon, serpent, etc.).

Question:
Keyboard instruments included the pip organ, harpsichord and what other instrument?

clavichord