In a Long-Day Plant,interrupting a Long Night with a Flash

In a long-day plant,interrupting a long night with a flash of light may trigger flowering.Conversely,if a long day is interrupted by short period of darkness,why doesn't a short-day plant flower?

A) Sunlight contains enough far-red light to inhibit the phytochrome induction of flowering.
B) Phytochrome degrades slowly in the dark to the inactive P_R form.A brief dark period during the day is not sufficient to inactivate phytochrome.
C) Phytochrome is only active in the dark.
D) The circadian clock is less active during the day than at night.
E) The cool temperatures at night interact with the phytochrome responsE.