B. acute reflection is the answer
Island isolation promotes allopatric speciation. Species are separated by the physical barrier which is in the ocean and islands are being isolated by each other by bodies of water.
There is no gene flow which occurs between the separated species. Living in the distinct island. The species get adopted by the island to the environment.
They then diverge as they separate species.
A control group of the experiment is the one in which no treatment or intervention is given. So, in your case, the pea plants in which was not subjected any of the fertilizers, will serve as a control group. This is a negative control. A positive control group is the one in which an established treatment is given, which definitely leads to the production of the desired character. So, in your case, a very good well-known fertilizer which has a positive control on the growth of the pea plant, would serve as a positive control.
Answer:
B. All antigen receptors produced by a single B or T cell are identical and bind to the same epitope.
Explanation:
Antigen receptors are antibody protein anchored to the B-cell membrane.
They are all identical when the antigen receptors is located on one type of B cell making Binding between the receptor and epitope to occur since its structures are complementary. It's not identical when the antigen receptors is located on different types of B cell