Concept:
Raja Ravi Varma was one of the most famous Indian painters of the nineteenth century.
He painted mythological subjects, portraits and scenes from Indian epics.
Step 1: Check Assertion (A).
Raja Ravi Varma was a great painter.
He produced mythological paintings and portraits.
So, Assertion (A) is correct.
Step 2: Check Reason (R).
His subjects made him popular among the public.
He also set up a printing press through which his images reached common people.
So, Reason (R) is also correct.
Step 3: Check whether Reason explains Assertion.
Ravi Varma became famous because of his popular mythological subjects and printed reproductions.
Therefore, the Reason explains the Assertion.
Step 4: Final conclusion.
Both statements are correct, and Reason is the correct explanation.
Hence:
\[
\boxed{\text{(A)}}
\]