Consider the Following Octahedral Complex Structures, Each Involving Ethylene Diamine

Multiple Choice

Consider the following octahedral complex structures, each involving ethylene diamine and two different, unidentate ligands X and Y. Which, if any, of the following pairs are optical isomers?

A) Structures 1 and 2
B) Structures 1 and 3
C) Structures 1 and 4
D) Structures 3 and 4
E) Structures 1, 2, 3, and 4