Species with planktonic larvae, whose adults live successfully only at the upper limit of the intertidal zone,

A) Will be able to settle successfully if their planktonic larvae are released for exactly 21 days
B) Will be able to settle successfully if their planktonic larvae are released at spring high tide and swim for 21 days
C) Will settle successfully if they are released in water and develop to the point of settlement in 14 days
D) Will settle successfully if first they are photopositive but are photonegative 14 days later