AP BIOLOGY

Detailed explanation-1: -So, the correct answer is ‘Photoperiod’

Detailed explanation-2: -Some types of plants require particular day or night lengths in order to flower-that is, to transition to the reproductive phase of their life cycle. By flowering only when day or night lengths reach a certain threshold, these plants are able to coordinate their flowering time with changes in the seasons.

Detailed explanation-3: -Flowering is controlled by environmental conditions and developmental regulation. The complexity of this regulation is created by an intricate network of signaling pathways.

Detailed explanation-4: -Long day plants require more exposure to light in order to initiate flowering. Flowering is initiated in them when they are exposed to a period of light greater than the critical photoperiod.