Phytochrome Prevents Seeds of Some Plants from Germinating When They

Phytochrome prevents seeds of some plants from germinating when they are in deep shade by the:

A) absorption of far-red wavelengths by chlorophyll.
B) absorption of red wavelengths by P_r.
C) absorption of far-red wavelengths by P_fr.
D) slow dark-conversion of P_fr to P_r.
E) slow dark-conversion of P_r to P_fr.