Given scientific fact as input, generate the question from this fact such that it can be answered from the input.
--------
Question: Deletions remove one or more nucleotides from the dna

Answer: Deletions remove one or more what from the dna?


Question: People stopped adding lead to gasoline because of environmental pollution.

Answer: Why did people stop adding lead to gasoline?


Question: The main functions of epithelia are protection from the environment, coverage, secretion and excretion, absorption, and filtration.

Answer:
The main functions of epithelia are protection from the environment, coverage, secretion and excretion, absorption, and this?