Step 1: Understanding the hierarchy of the caste system.
The caste system in Hindu society is traditionally divided into four main groups:
- Brahman (C): The highest caste, responsible for teaching, priesthood, and intellectual pursuits.
- Ksatriya (B): The warrior and ruler class, responsible for protection and governance.
- Vaishya (A): The merchant class, responsible for trade, agriculture, and wealth generation.
- Shudra (D): The lowest caste, responsible for serving the other castes in various menial tasks.
Step 2: Conclusion.
The correct hierarchical order is C, B, A, D.
Final Answer:
\[
\boxed{\text{The correct answer is 2. C, B, A, D.}}
\]