What Is the Most Likely Explanation for Why Daphnia Switch

What is the most likely explanation for why Daphnia switch from asexual to sexual reproduction when certain environmental conditions deteriorate?

A) Sexual reproduction can produce more offspring faster than asexual reproduction,thus increasing the likelihood the species will survive hard times.
B) Although energetically expensive,sexual reproduction creates all genetically superior individuals that are more likely to withstand hard times.
C) Asexual reproduction is too energy intensive to maintain during hard times.
D) Sexual reproduction creates individuals that are more genetically diverse,thus increasing the likelihood of some members surviving hard times.