Answer : 2. "ethnic"
Explanation :

A. National census does not identify ethnic groups within India.

B. Here are examples of some specific groups identified by the national census.

1. Tribal Groups: Santhal, Gond, Adivasi, Bodo, Meena, Kushwaha

2. Religious Groups: Hindu, Muslim, Christian, Sikh, Buddhist, Jain, Parsi

3. Linguistic Groups: Hindi, Bengali, Marathi, Tamil, Telugu, Urdu, Gujarati, Kannada, Punjabi, Assamese