Binding of Norepinephrine or Epinephrine to A(n) Receptor Will Activate

Binding of norepinephrine or epinephrine to a(n) receptor will activate an inhibitory G protein which decreases the activity of adenylate cyclase and therefore cAMP synthesis while the
Binding of these two neurotransmitters to a receptor will do the exact opposite.

A) a_{2 :} fi₁
B) a_{1 :} a₂
C) fi_{1 :} fi₂
D) fi_{2 :} fi₁
E) a_{2 :} a₁