The assertion (A) is that Ashoka annexed Kalinga to the Mauryan Empire. This statement is true. Emperor Ashoka did indeed annex Kalinga into the Mauryan Empire after a brutal and bloody war, which greatly affected him and led him to adopt Buddhism and the principle of non-violence.

The reason (R) provided is that Kalinga controlled the land and sea routes to South India. This statement is also true. Kalinga`s strategic location on the eastern coast of India allowed it to control both land and sea trade routes, making it highly desirable for any empire looking to extend its reach and influence.

As per option 1 - both A and R are true and R is the correct explanation of A. This is the correct answer. The control of trade routes in that region was one of the primary reasons that led Ashoka to annex Kalinga into his empire.

So, both the assertion and the reason are correct facts, and the reason correctly explains why the assertion took place, thereby making option 1 the right answer.