Answer:
Option A, bacilli
Step-by-step explanation:
Bacteria's are classified on the basis of their shape into the following categories -
a) Spherical or round shapes - Such bacteria's are knowns as coccus
b) Rod Shaped or cylindrical shaped - Such bacteria's are known as Bacillus
c) Twisted or turn around shape - such bacteria's are known as Spiral
d) comma shaped - Such bacteria's are called as vibrios
Hence, option A is correct as rod shaped bacteria's are known as bacilli.