Step 1: Understanding the Concept:
The question requires matching the Niyamas, which are the second limb of the eight limbs of yoga described in Patañjali's Yoga Sūtras, with their correct English descriptions.
Step 2: Detailed Explanation:
Let's define each Niyama from List-I and match it with the descriptions in List-II.
(A) Śauca: This Niyama refers to purity and cleanliness, both externally (of the body) and internally (of the mind, speech, and thoughts). This perfectly matches (I) Purity of body, mind, thought.
(B) Santoṣa: This translates to contentment. It is the practice of accepting and being happy with what one has, rather than craving for what one doesn't have. This perfectly matches (II) Positive Contentment.
(C) Tapas: This refers to austerity, self-discipline, and the spiritual effort or "heat" that purifies the body and mind. It involves practices that build willpower. This perfectly matches (IV) Austerity.
(D) Svādhyāya: This means self-study or study of the self. It includes introspection as well as the study of sacred texts that lead to self-realization. This perfectly matches (III) Self-study, introspection.
Step 3: Final Answer:
Based on the definitions, the correct pairings are:
A - I
B - II
C - IV
D - III
This combination corresponds to option (2).