Step 1: Understanding the Question:
• The question gives an Assertion A that Pranayama is the fourth limb of Ashtanga Yoga and a Reason R describing Pranayama.
Step 2: Detailed Explanation:
• Assertion A is true: the limbs are Yama, Niyama, Asana, Pranayama, Pratyahara, Dharana, Dhyana and Samadhi, so Pranayama is fourth.
• Reason R is true: Pranayama in the Yoga Sutra includes Puraka, Rechaka and Kumbhaka, and R explains what the fourth limb consists of.
Step 3: Final Answer:
The correct option is (A) Both A and R are true and R is the correct explanation of A.