Coordination isomerism is caused by the interchange of ligands between the
A Cis and trans structure
B Complex cation and complex anion
C Inner sphere and outer sphere
D Low oxidation and higher oxidation states

Hint: The coordination isomerism is the structural isomers in which the molecular formula is the same but the bonding of ligands with the central metal atom is different. As the name suggests that the coordination isomers are those compounds whose molecular formula will the same but different in coordination bonding (bonding by donating lone pairs by ligands) is different. The cis and trans isomers are stereoisomers (geometrical isomers) that differ in the arrangement of ligands in space. So, cis and trans structures cannot be coordination isomers.

Complete answer:Mostly the coordinate complex compound we know is the one in which the anionic or cationic part of the complex compound is complex and another part is not complex. But when both part of the coordinate complex compound (anionic and cationic part) is complex means both parts contain one central metal which is surrounded by a ligand or number of ligands, then the coordination isomerism take place in such coordinate complexes.
When the ligands of the cation and anionic part exchange with each other then we said this process coordination isomerism. This means when one or more than one ligand of the cationic part becomes a ligand of the anionic part and the anionic part’s ligand becomes a ligand of the cationic part or vice verse in equal number then the resulting compounds are the coordinate isomers of each other.
Thus, the correct option is B.

Note: The example of coordination isomers are\[{{\left[ Co{{\left( N{{H}_{3}} \right)}_{6}} \right]}^{+3}}\text{ }{{\left[ Cr{{\left( CN \right)}_{6}} \right]}^{-3}}\]. The taken complex is such in which both the anionic and cationic part is a complex. Now when one or more than one ammonia ligand of cobalt complex (cation) forms a coordination bond with chromium complex (anion) and the same number of cyanide ligands from anion form a coordination bond with a cationic part such as
\[{{\left[ Co{{\left( N{{H}_{3}} \right)}_{5}}\text{ }CN \right]}^{+3}}\text{ }{{\left[ Cr{{\left( CN \right)}_{5}}\text{ }N{{H}_{3}} \right]}^{-3}}\]and so on
These are the coordination isomers and the phenomenon is known as coordination isomerism.