Relevant diagram

ATII constricts the efferent arteriole. ACE inhibitors block the ACE-mediated conversion of ATI to ATII.

• ACEI prevent the conversion from Angiotensin I to Angiotensin II. It leads to a dilation of the efferent artery which is constricted under ATII's effect.

• The point of this question is to realize which structure is the efferent artery. In the picture, the label C is Juxtaglomerula cells, the adherent part of the label E is Macula densa of DCT. Those structures are in close contact with the afferent artery to sense sodium and perfusion pressure, so the F is the efferent artery.