Ans.
In human body, three types of blood cells are present, which include red blood cells, platelets, and white blood cells. Although these cells are started out alike, they show different shapes, sizes, and functions due to instructions that differentiate them into different types. These instructions are given by particular chromosomes present in the cells as the chromosomes consist of DNA that provides information to the cells, which is responsible for characteristic behavior of that cell.
Hence, the correct answer for the blank is 'B) chromosomes.'