An example of an agranulocytic leukocyte is a/an a. neutrophil. b. lymphocyte. c. basophil. d. erythrocyte.

The leukocytes are the White blood cells (WBCs). These cells are also known as the immune cells, and are divided into two categories, granulocytes and agranulocytes based on the presence and the absence of the granules in their cytoplasm.  

The lymphocytes and the monocytes are the agranulocytes found in the blood.  

Hence, in this case, the correct answer would be Option B, lymphocytes.