Use the following list of complexes to answer the questions.

There may be more than one correct choice for each answer.

(a) Which complex has three isomers, two of which are enantiomers?

(b) Which complex may have linkage isomers?

(c) Which complexes cannot form optically active isomers?

(d) Identify the complex that has the greatest number of possible isomers. Show the structures for all of the isomers.