Assertion: All political parties support reserving seats for the ‘backward classes' in education and employment.
Reason: Political parties have recognised that the social and political claims of the backward castes need to be accepted.

Both the Assertion and the Reason are correct and the Reason is the correct explanation of the Assertion.

Political parties have recognised that the social and political claims of the backward castes need to be accepted.  As a result, all political parties now support reserving seats for the ‘backward classes’ in education and employment. Political parties are also willing to ensure that the OBCs get a fair share of power.