Final answer:
The term that means pertaining to the grain is "Granivorous." It describes animals that feed on grain. Granulocytes contain granules and are a type of white blood cell effective against bacteria.
Step-by-step explanation:
The term that could best mean "pertaining to the grain" is "Granivorous" (D). This term is specifically used to describe animals that feed primarily on seeds or grain. It directly relates to dietary habits based on grains.
Granulocytes are a type of leukocyte or white blood cell, which can be described as abundant, granular, and especially effective against bacteria. They are produced in red bone marrow and have a lobed nucleus. While granules are not totally lacking in agranular leukocytes, such as monocytes and lymphocytes, they are fewer and less obvious.
White blood cells (also called leucocytes) can be classified as granulocytes or agranulocytes, and they defend the body against bacteria and viruses. Granulocytes contain multiple granules packed with substances like histamines and are effective against bacteria.