Question

In an experiment to study the effect of ultraviolet light on bacteria, it was concluded that ultraviolet light has a sterilizing effect on bacteria. Which of these observations could have led to this conclusion?
A) Ultraviolet light stopped the replication process of bacteria.
B) Bacterial colonies exposed to ultraviolet light continued to replicate.
Eliminate
C) Bacterial colonies exposed to ultraviolet light became resistant over time.

Answer 1

A) Ultraviolet light stopped the replication process of bacteria. 
Stopped or slowed this process, hint the sterilization.  

The question doesn't directly ask this but, after a while a lot of bacteria become immune to treatment especially antibiotics. 

Answer 2

Answer A) Ultraviolet light stopped the replication process of bacteria.

UV radiation is the mutagen which means it can cause mutation in the genome of the living organisms such as humans, bacteria, virus and other microorganisms. These rays are harmful for bacterial colonies when particularly exposed to wavelength of 260nm to 270nm. These radiations breaks molecular bonds within the bacterial DNA, these radiations results in the formation of thymine dimers which can kill the bacteria.

On the basis of the above description, Ultraviolet light stopped the replication process of bacteria is the relevant option.

.