Postcolonial literature deals with the effects of colonialism on colonized societies.
It questions the power relations created by colonial rule.
It also criticizes domination, exploitation, racial superiority, cultural control, and political oppression.
So Assertion (A) is correct.
Now consider Reason (R).
Postcolonial literature often highlights questions of identity.
It shows how colonized people struggle with language, culture, race, nation, and selfhood.
It also presents cultural conflict between colonizer and colonized.
Resistance is also a major theme because postcolonial writers challenge colonial authority and colonial narratives.
Therefore, Reason (R) is also correct.
Reason (R) explains Assertion (A) because issues of identity, cultural conflict, and resistance are the ways through which postcolonial literature questions colonial power structures.
Hence, the correct answer is:
\[
\text{Both (A) and (R) are correct and (R) is the correct explanation of (A).}
\]