Addition of a Functional Group to the Pro-R Carbon of Glycerol

Addition of a functional group to the pro-R carbon of glycerol places that group on carbon _____ while addition of a second functional group to the pro-S carbon of glycerol places the second group on carbon _____ of sn-glycerol.

A) 1; 2
B) 1; 3
C) 3; 2
D) 3; 1
E) 2; 2