For Plants That Flower in Response to Photoperiodic Stimuli, the Most

For plants that flower in response to photoperiodic stimuli, the most critical determinant in the light-dark cycle is the

A) temperature.
B) length of the dark period for short-day plants and length of the light period for long-day plants.
C) length of the light period for short-day plants and length of the dark period for long-day plants.
D) length of uninterrupted dark.
E) length of uninterrupted light.