TASK DEFINITION: Write a correct answer to the given question based on its associated fact. Make sure that your answer is contained in the associated fact. Don't be creative and introduce any new word that is not mentioned in the associated fact! Remember that the associated fact has been rearranged to form the question. So, the correct answer words must lie within the associated fact. The correct answer can be a word, phrase, or even a sentence.
PROBLEM: Fact: Viruses are viewed by illuminating electrons. 
Question: What of the following can only be viewed by illuminating electrons?

SOLUTION: viruses.

PROBLEM: Fact: Axons transmit brain impulses to other cells. 
Question: What transmits brain impulses to other cells?

SOLUTION: Axons.

PROBLEM: Fact: echinoids lack a centralized nervous system. 
Question: What do echinoids lack?

SOLUTION:
centralized nervous system.