In this task, you are given a question and an answer, you would be asked to create the sentence based on the Question-Answer provided. It should be contained within the Question-Answer provided.

[Q]: Question: Volume is another way of measuring what? Answer: material
[A]: Volume is another way of measuring material.

[Q]: Question: When food enters the stomach after a period of fasting, a drop in what initiates the conversion of pepsinogen to pepsin? Answer: ph
[A]: Ph food enters the stomach after a period of fasting, a drop in what initiates the conversion of pepsinogen to pepsin.

[Q]: Question: Mollusks can be divided into how many classes? Answer: seven
[A]:
Mollusks can be divided into seven classes.