Step 1: Understanding the assertion (A).
Isometric training involves static exercises where the muscle exerts force without changing its length. It is commonly used to develop strength in muscles.
Step 2: Understanding the reason (R).
Fartlek training is a form of interval training used to improve stamina and endurance. However, it is unrelated to the development of strength as mentioned in the assertion.
Step 3: Conclusion.
While the assertion (A) is correct, the reason (R) does not correctly explain (A) because Fartlek training is primarily for stamina and endurance, not strength. Therefore, the correct answer is (C).
Final Answer: (C) (A) is right but (R) is not correct explanation of (A).