The answer for your question is A.
Since it’s natural environment is very acidic, putting pepsin in a very alkaline environment would cause it to denature.
Answer: Option A.
Different beaks were available
Explanation:
Variation is the difference between traits, cells, or characteristics between organisms of any species which is caused by change in genetic information or effect of environmental factors on the expression of genes.
From the question, different beaks were available because there is variation or differences in shapes, sizes and expression.