Fact 1: Bottleneck effect occurs when a population suddenly gets much smaller.

Fact 2: Genetic variation can be reduced by random genetic drift, population bottlenecks, founder effect.

Given the two facts above, answer the question "What can be reduced when a population suddenly gets much smaller?" with the following options: 
- Pollution
 - The size of the Earth
 - Greenhouse gasses
 - The size of bottlenecks
 - The size of the environment
 - Genetic variation
 - Plant growth is reduced
 - Quality of life


 

      Genetic variation   