Class I and Class II Aminoacyl-TRNA Synthetases Differ in

Class I and Class II aminoacyl-tRNA synthetases differ in
I. their major structures
II. the general size of aa that fits their active sites
III. exposure of their active sites
IV. fidelity in proofreading

A) I only
B) I and III
C) I, III and IV
D) II, III and IV
E) I, II and III