Let's analyze the given statement of Assertion (A) and Reason (R) to determine the correct relation between them.
The Reason (R) provided is the correct explanation of the Assertion (A). The process of creative visualisation requires a certain level of mental and physical relaxation, which is corroborated by the reason given. Thus, both statements are true, and Reason (R) precisely explains why creative visualisation is effective.
Therefore, the correct option is: Both Assertion (A) and Reason (R) are true, and Reason (R) is the correct explanation of Assertion (A).