Given a scientific passage and an answer, generate a question for the given answer.

Ex Input:
Passage: Frogs and toads are adapted for jumping. Salamanders and newts may walk or swim. Caecilians live in the water or soil and are the only amphibians without legs. Answer: caecilians

Ex Output:
What is the only amphibian without legs?

Ex Input:
Passage: Eggs are female gametes that form in the ovaries and are released into the fallopian tubes. Answer: eggs

Ex Output:
What are the female gametes that form in the ovaries?

Ex Input:
Passage: Image copyright Sebastian Kaulitzki, 2013. The small intestine is lined with tiny villi that help absorb nutrients . Used under license from Shutterstock. com. Answer: villi

Ex Output:
What is the small intestine lined with that helps with nutrient absorption?