Step 1: Understanding the Concept:
The question asks for the sociological term for the system of relationships based on blood and marriage.
Step 2: Detailed Explanation:
- (A) Kinship: This is the exact definition of kinship. It is the web of social relationships that are based on common ancestry (consanguinity), marriage (affinity), or adoption. This system regulates the rights, obligations, and interactions among relatives or 'kin'.
- (B) Jajmani, (C) Zamindari, and (D) Mahalwari are all socio-economic systems related to land tenure and the exchange of goods and services in traditional and colonial India, not the regulation of family relations.
Step 3: Final Answer:
The system which regulates the mutual relations of kins is called Kinship.