Free play emphasizes creativity, communication, and interest retention, making it beneficial for social and cognitive development. However, improving sports performance is associated more with structured or organized play. Thus, option (c) is the correct choice.
Assertion (A): The sum of the first fifteen terms of the AP $ 21, 18, 15, 12, \dots $ is zero.
Reason (R): The sum of the first $ n $ terms of an AP with first term $ a $ and common difference $ d $ is given by: $ S_n = \frac{n}{2} \left[ a + (n - 1) d \right]. $