Some scientists believe that the relationship between mice and humans

I am going with option D.

We need to strengthen below conclusion/argument:
Despite numerous predators and humanity’s enmity, mice have distributed themselves more widely across the planet than any other mammal except humans. Mice reproduce rapidly and, more important to their survival, they have the ability to adapt to an extraordinary range of habitats. Should the environment ever become too extreme to support human life, naturalists predict that mice would be able to adapt and survive.

Conclusion: Mice will survive even where humans cannot survive.

Options:
(A) The size of the mouse population is limited by the availability of food. - We are not focusing on the food and then the option does not mention anything about where the food is available. So irrelevant to the argument.

(B) Under optimum conditions, mice reproduce every four weeks, with five to seven pups per litter. - Great. This helps but then ignores anything about humans. Let's say it is three weeks instead of four weeks there won't be any impact to the conclusion.

(C) Fossil remains prove that mice inhabited North America prior to the arrival of humans. - Inhabited prior to arrival of humans does not strengthen the fact that mice can survive in environments where humans cannot.

(D) Mice have colonized an island near Antarctica which is too bleak and harsh to support human life. - Clearly gives us an example of the conclusion. This should be the answer but let's check E.

(E) A significant percentage of the world’s mouse population lives in urban areas. - The argument already mentioned that mice's habitat is wast so it does not strengthen the conclusion in any way.