Answer:
b) natural variation w/in a species
Explanation:
All the answer you put are evidence of evolution also I have done this before.
If all humans had the same DNA, and one person got the cold, everyone would die at some point. The more diversity there is the more chance of surviving an outbreak or natural disaster or something. Think of the flu. there are HUNDREDS of strains out there. some are resistant to our medicines and others aren't.
<span>Intrinsic factor is a glycoprotein principally secreted by the parietal cells of the stomach. This secretion is needed to produce mature erythrocytes. Its secretion is governed by the same biochemical processes that regulate acid secretion and its action is to assist in the absorption of vitamin B12.</span>
I think the answer in this is c because it shows how the scientist worked in feilds
