There are twenty-five protists living in a tide pool. They are able to choose between asexual reproduction and sexual reproduction.

Under which condition should they choose sexual reproduction?

A. A bacteria has colonized the tide pool, infecting the protists.
B. The tide pool water remains at the same depth year after year.
C. The temperature of the tide pool varies very little day to day.
D. The 25 protists die but leave 25 offspring in their place.