All the knowledge related to the Vedic Period (C. 1750-500 BCE) in which the Indo-Aryans brought specific religious tradition, plus their farming and agricultural practices to northern India - area in which they settled - is extracted from the Vedas. Known as the oldest scriptures in the Hindu religion, these historic records were composed by the Aryans in Sanskrit.
Answer to question 1 is C. The Vedas provide a record of how the Indo-Aryans lived.
Originated in Ancient India, the Castes are social structures in which people were (and still are although to a lesser extent) ranked, named, married, and were part of a family/group that provided certain obligations and a level of status, all of it just defined by birth.
The two main concepts behind the system are Varna (The established four main classes: Brahmins, Kshatriyas, Vaishyas, and Shudras). The second concept is Jati: These are complex social groups that are not part of the higher level Varnas and are more flexible and diverse.
Answer to question 2 is C. A system of social classes based on birth evolved.