Assertion (A): Two players Sania and Ashma play a tennis match. If the probability of Sania winning the match is 0.79, then the probability of Ashma winning the match is 0.21.

Reason (R): The sum of probabilities of two complementary events is 1.

1. Assertion (A) is true, but Reason (R) is false.

2. Assertion (A) is false, but Reason (R) is true.

3. Both Assertion (A) and Reason (R) are correct, and Reason (R) is the correct reason for Assertion (A).

4. Both Assertion (A) and Reason (R) are correct, and Reason (R) is incorrect reason for Assertion (A).

Given, the probability of Sania winning the match = 0.79.

As we know that the sum of probabilities of two complementary event is 1.

⇒ P(Sania wins) + P(Ashma wins) = 1

∴ Reason (R) is true.

⇒ 0.79 + P(Ashma wins) = 1

⇒ P(Ashma wins) = 1 - P(Sania wins)

⇒ P(Ashma wins) = 1 - 0.79

⇒ P(Ashma wins) = 0.21

∴ Assertion (A) is true.

∴ Both Assertion (A) and Reason (R) are correct, and Reason (R) is the correct reason for Assertion (A).

Hence, option 3 is the correct option.