The gastric chief cells of the stomach secrete enzymes for protein breakdown (inactive pepsinogen, and in infancy rennin). Hydrochloric acid activates pepsinogen into the enzyme pepsin, which then helps digestion by breaking the bonds linking amino acids, a process known as proteolysis.
A should be the products and D should be the reactants. So D should be the answer.
The sign's glass absorbed 25466.7 J
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Further explanation</h3>
Given
The temperature of glass : 23.5 °C to 65.5 °C
mass = 905 g
the specific heat capacity = 0.67 J/g °C
Required
Heat absorbed
Solution
Heat absorbed by sign's glass can be formulated :

ΔT=65.5 - 23.5 = 42

Many atoms if they are radioactive isotopes will loss protons and neutrons as radiation in order to gain and become more stable
hope that helps
Answer: There is no list in your question. But the three factors in which natural selection occurs are:
1. A struggle for existence,
2. Variation and
3. Inheritance
Explanation:
Darwin’s theory of natural selection is the way in which organisms change overtime.
These changes allow organisms to become better adapted to their environment and increase their chances for survival.
The three major factors through which natural selection occurs are:
1. A struggle for existence,
2. Variation and
3. Inheritance
Darwin’s theory of natural selection will occur if the three conditions above are met and unless these factors are in place, natural selection will not occur.