Assertion: Linkage isomerism arises in coordination compounds containing ambidentate ligand.

Reason: Ambidentate ligand has two different donor atoms.

1.  Both assertion and reason are true and the reason is the correct explanation of assertion.

2.  Both assertion and reason are true and the reason is not the correct explanation of assertion.

3.  Assertion is true but the reason is false.

4.  Assertion is false but the reason is true.

Hint: Linkage isomerism is because of ambidentate ligand

Linkage isomerism arises in coordination compounds containing ambidentate ligands because ambidentate ligand has two different donor atoms. e.g., SCN, NO${}_{2}$ etc.

The example of linkage isomerism is as follows:

[(NH3)5Co-SCN]2+ and [(NH3)5Co-NCS]2+

Hence, option 1 is the answer.