Input question: Ornithology is the study of what?

Output answer: birds

Input question: In humans, atelectasis affects which part of the body?

Output answer: lungs

Input question: 'Motion Pictures Experts Group Format I (or II), Audio Layer III' is better known as what three-characters?

Output answer: mp3

Input question: Oil is traditionally sold in barrels. How many gallons in a barrel of oil?

Output answer:
42