Which of the following is the best evidence

that digestion involves chemical change?

A Time is required to accomplish results.

B The products' mass equals the reactants'

mass.

C Different compounds are involved.

D New substances are produced.

I think it is B. Because A has nothing to do with chemical changes because any change takes an amount of time, C because in a mixture different compounds are involved, It could be D though but A new substance is produced in other changes too thus it must be B.