People with Schizophrenia Are More Likely to Have Been Born

People with schizophrenia are more likely to have been born during the winter months. One explanation for this phenomenon is that

A) people born during these months are more likely to be exposed to the flu virus while still in the womb.
B) cold temperatures slow down neuronal development.
C) summer heat negatively affects the genetic maternal in sperm at the time of conception (9 months earlier) .
D) Eggs released during the summer-9 months earlier-are more likely to contain genetic errors.