Correct option is A
The correct answer is (a) Cultural diversity.
By introducing students to art forms that emerged during the freedom struggle from different parts of the country, the teacher is exposing them to a variety of cultural expressions. Art is a reflection of the culture in which it is created, and by examining art from different regions, students can learn about the diverse cultures of India.
Linguistic diversity, religious diversity, and regional diversity are all important aspects of India's diversity, but they are not directly brought into the classroom by the teacher's actions. The teacher is specifically focusing on cultural diversity by introducing students to art forms from different parts of the country. Therefore, the answer is (a) Cultural diversity.