Which two statements about natural selection are true? 1) Only variations that help individuals avoid predators can become more common through natural selection. 2) The result of natural selection in a population depends on the population's environment. 3) Natural selection can cause an individual to gain new advantageous variations during its life. 4) Natural selection causes advantageous variations to become more common over many generations.

What you are looking for

Natural selection is about how heritable traits change in frequency in a population over generations. So the true statements should mention (1) environment-based differences in survival or reproduction and (2) changes across many generations, not changes within a single individual.

Checking each statement

1) Only variations that help individuals avoid predators... False. Traits can be favored for many reasons besides predator avoidance, such as better access to food, resistance to disease, tolerance to temperature, or higher mating success.

2) The result of natural selection... depends on the environment. True. A trait that is helpful in one environment may be neutral or harmful in another. For example, thick fur can be advantageous in cold climates but disadvantageous in hot climates.

3) Natural selection can cause an individual to gain new advantageous variations during its life. False. Natural selection does not create new traits in an individual. New genetic variation mainly comes from mutation and recombination, and selection acts on existing heritable variation by changing which individuals leave more offspring.

4) Natural selection causes advantageous variations to become more common over many generations. True. If a variation is heritable and increases reproductive success, its allele(s) tend to increase in frequency across generations.

Quick summary

Correct choices: 2 and 4.