Which of the following is a good example of metapopulation?

1. Which of the following is a good example of metapopulation?
a. Two populations of rain forest monkeys, separate by a 20,000 foot mountain range
b. Populations of prairie plants in a landscape made up mostly of open prairie, with some woodlots mixed in
c. Fish that live in a string of rapids in a river, separated by stretches of deeper water
d. Bears which live in a large continuous forest

My best guess would be A, but I don't know for sure.

2. In a metapopulation situation, the bigger challenge for long-term species survival is
a. the average size of habitat patches or islands
b. the average distance between habitat patches or islands
c. the kind of habitat which occurs in between the habitat patches or islands

I would guess A, or maybe B for question 2.