Answer:
I'm pretty sure its B. voluntary-response bias
Hi,
I think that you're missing some options, but here they are (let me know if I'm right!
-A population of wolves was introduced
-The amount of disease in the deer population decreased
-More grass was planted
Now, if the gene diversity decreased, it means that a lot of deer died. This could happen because wolves were introduced -this is the correct answer, and the wolves ate some deer.
Neptune takes the longest to orbit the sun because its distance from the sun is really far away.
hope i helped :)