Appearance of antibiotic-resistant bacteria is an example of

Options

A. adaptive radiation
B. transduction
C. pre-existing variation in the population
D. divergent evolution.

Answer

C

Explanation

When a bacterial population encounters a particulars antibiotic, those sensitive to it die, But some bacteria having mutations become resistant to the antibiotic. Such resistant bacteria survive and multiply quickly as the competing bacteria have died. Soon the resistance providing genes become widespread and entire bacterial population becomes resistent.