Concept:
Marxian theory is based on conflict and class struggle between social classes.
Step 1:
Marxian theory is not functional in nature; it is primarily a conflict-oriented theory.
\[
A \text{ is incorrect}
\]
Step 2:
Karl Marx emphasized exploitation and conflict between the bourgeoisie and proletariat.
Step 3:
Conflict theory explains class struggle and competition for power and resources in society.
\[
R \text{ is correct}
\]
Step 4:
Functionalism focuses on social stability, whereas Marxian conflict theory focuses on inequality and struggle.
Step 5:
Therefore, Assertion is incorrect but Reason is correct.
\[
\boxed{\text{(4) (A) is not correct but (R) is correct}}
\]