It is B, it could also be D, but it is most likely B. Hope this helps.
Answer: (A) Natural selection tend to reduce genetic variation as there was a smaller distribution of beak depths, but it tends to select for the most fit phenotypes, as there was an increase in average beak depth after the drought.
Explanation: The picture below shows proof if needed. On USATP
Plants such as the cactus reside in the desert biome.
Neuroglial Cells is the answer
Reflex action in the diagram would be the response. Diagram extracted from online.