Clover Will Flower If Exposed to 8 Hours of Dark

Multiple Choice

Clover will flower if exposed to 8 hours of dark and 16 hours of light.It will not flower if exposed to 16 hours of dark and 8 hours of light.However,if the 16 hours of dark is interrupted with a brief period of light the clover will flower.Which triggers clover to flower?

A) short dark periods
B) long dark periods
C) short light periods
D) long light periods