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

Ex Input:
Passage: An ecosystem includes the living organisms (all the populations) in an area and the non-living aspects of the environment ( Figure below ). An ecosystem is made of the biotic and abiotic factors in an area. Answer: ecosystem

Ex Output:
What includes the living organisms in an area and the non-living aspects of the environment?

Ex Input:
Passage: Neurons are usually classified based on the role they play in the body. Two main types of neurons are sensory neurons and motor neurons. Answer: aphotic zone

Ex Output:
What do you call the zone in a body of water where there is too little sunlight for photosynthesis?

Ex Input:
Passage: Benzoic acid crystals in polarized light are pictured above. Benzoic acid is widely used as a food preservative, either as the carboxylic acid or as the sodium benzoate salt. This compound is most effective when added to acidic foods such as fruit juices and soft drinks. The major industrial source of benzoic acid is the partial oxidation of toluene with oxygen. The process is inexpensive and environmentally benign. Answer: benzoic acid

Ex Output:
What type of acid is often used as a preservative for acidic foods such as fruit juices?