On Pacific islands, a newly arrived gecko species, the house gecko, is displacing the previously established mourning gecko in urban areas, but populations of the two species are more stable in rural areas far from human settlement. The house gecko does not attack the mourning gecko, but in areas where insects congregate it prevents the mourning gecko from feeding on them.
Which of the following contributes most to an explanation of the difference between gecko populations in urban and rural areas?
A. In urban areas, geckos are valued because they eat so many insects.
B. Geckos defend territories against other members of the same species.
C. House geckos that arrive on islands are carried there in boats and planes.
D. places where there are lighted buildings, insects tend to gather around the light.
E. Mourning geckos are all females and reproduce asexually, but house geckos reproduce sexually.

The correct option is D: places where there are lighted buildings, insects tend to gather around the light.

Explanation:

We are looking for an option that provides an explanation of the difference between gecko populations in urban and rural areas

Option A does not explain any difference between the both species of geckos in urban and rural areas

Option B is the same as A, and does not explain any difference between the both species of geckos in urban and rural areas

Option C is also wrong because it provides an invalid information about what we are looking for.

Option E is also wrong because it provides information on how geckos reproduce, which is not what we are looking for.

These options provide information on how geckos reproduce, why people value them, and how they are transported to the Island, and about defending territories in which we do not know the type of gecko or the territories they are defending.

The correct option is D because places where we have lighted building is the URBAN AREAS and "insects tend to gather around the light", geckos are found where there are insects congregate and house geckos, prominent in Urban Areas, will not allow the mourning geckos to feed on the insect, which is the underlying reason for their displacement.