I would say that the answer to this question is most likely B or D.
The answer is Crescent.
<span>During a crescent moon, we see one whole side of the Moon here on Earth.
</span>
<span>New moon -</span><span> the illuminated side of the Moon is away from the Earth. only
the shadowed side can be seen. </span>
><span>Waning gibbous - </span><span>the Moon is less than fully illuminated, but, is more than
half.</span>
<span>>Full Moon - Brightest lunar phase.</span>
The correct answer is antigens and epitope.
An antigen is a substance which triggers an immune response in an organism. This can be either a foreign substance, such as a pathogen, or a specific part of the host organism (in this case this is an autoimmune response). The presence of an antigen activates a specific part of the immune system, called antibody. Each antigen has a specific antibody, which is tailored by the immune system accordingly. More specifically, the antibody has a specific structure, called paratope, which is complementary and binds like a key to a specific structure of the antigen, called epitope.