The three dienes(red) associated with compound A - C do not react similarly with a dienophile. One diene has a low activation barrier and reacts rapidly; one diene has a high activation barrier and any product formed will be highly reactive; and one diene is inactive. Select the answer that lists dienes A, B, and C from most reactive toward a Diels-Alder reaction to unreactive.
A) c,b,a
B) a,b,c
C) a,c,b
D) b,a,c