B
Below is a question with multiple-choice answers. Choose the correct option based on your reasoning.

### Question:
The cheetah population around the world has decreased because of poaching and loss of habitat. The surviving population is found to have similar alleles. Which factor is endangering the species' survival the most?

### Choices:
A. harmful genetic mutations
B. shrinking of the gene pool
C. decrease in competition
D. increase in adaptations

### Answer:
