cis-[CoCl2(NH3)4]+

Geometric or optical isomerism are possible with coordination complexes. It would not be out of character for the MCAT to involve a passage with questions of cis vs. trans isomerism involving a complex, or to introduce basic stereochemical considerations that go along with chirality in the context of coordination complexes. Putting fundamentals into what they suspect is an unusual context for the student is a strategy they use all the time to distinguish conceptual understanding from rote learning.