instruction:
Given an trivia question precisely answer the question with a word/phrase/name. External resources such as Wikipedia could be used to obtain the facts.
question:
Leonora is the heroine of which opera premiered in 1805?
answer:
fidelio


question:
Omega is the last letter of the Greek alphabet, which is the penultimate letter?
answer:
psi


question:
Which letter comes between rho and tau in the Greek alphabet?
answer:

sigma