Long prose romances were written by Greek writers in the early centuries AD.
So Assertion (A) is correct.
Reason (R) also gives a correct description of many ancient romances.
Such romances often involve separated lovers, dangerous journeys, adventures, escapes, and final reunion.
However, Reason (R) describes the subject matter of such romances.
It does not directly explain the historical fact that Greek writers wrote them in the second and third centuries AD.
Therefore, both (A) and (R) are correct, but (R) is not the correct explanation of (A).