The presence of variation in the size and shape of bacterial cells of the same species is known as
a. pleomorphism
b. pseudomorphology
c. sarcina
d. chemotaxis

Correct answer is a pleomorphism

Explanation:

Some bacteria have the ability to change their shape and size which is called pleomorphism. The bacteria which change their shape and size are called pleomorphic bacteria.  

These bacteria change their shape due to the change in the external environment condition. For example, bacteria can from rod to coccus shape as their environmental condition changes.  

Some examples of pleomorphic bacteria are mycoplasma, some members of the Deinococcaceae family, helicobacter pylori, etc. So the correct answer is a.

that scientist would be robert hooke