Variations within a species are an important part of Charles Darwin's theory of evolution. Which example can be explained by individual variation? The food source in a lake is not enough to support the bass population, but it can support the trout.
A population of brown bears has doubled in the past 10 years as its habitat size has increased.
Owls and foxes compete fiercely against each other for small rodents in their habitat.
Brightly colored cardinals are better able to survive and to reproduce than darker cardinals.

Two bestfriends in a room. They might kiss

Explanation:

Brightly colored cardinals are better able to survive and to reproduce than darker cardinals.

Explanation:

Variation definition- any difference between cells, individual organisms, or groups of organisms of any species caused either by genetic differences or by the effect of environmental factors on the expression of the genetic potentials (phenotypic variation). Variation may be shown in physical appearance, metabolism, fertility, mode of reproduction, behavior, learning and mental ability, and other obvious or measurable characters.

The brightly colored cardinals are able to survive and reproduce because of variation in a species. Your question states "Variations within a species", so with that clue we can eliminate A and C (examples of competition) And B does not mention variation in a species. So we can conclude that D is the correct answer, since the brighter cardinals are able to survive and reproduce better than the darker cardinals, this is an example of Variation.

1. dermis

2. chemical

3. urine

4. viruses

5. antibodies