Ratan Thylam, the famous personality from Manipur, is known for his work in the field of :

Sports
Music
Theatre
Social reform

Ratan Thylam is a famous personality from Manipur who is known for his work in the field of social reform. He is a social activist who has been working for the upliftment of the poor and marginalized people of Manipur. He has also been working for the promotion of education and health in Manipur.

Option A: Sports. Ratan Thylam is not known for his work in the field of sports. He is not a sportsperson and has not made any significant contribution to the field of sports.

Option B: Music. Ratan Thylam is not known for his work in the field of music. He is not a musician and has not made any significant contribution to the field of music.

Option C: Theatre. Ratan Thylam is not known for his work in the field of theatre. He is not an actor or director and has not made any significant contribution to the field of theatre.

Option D: Social reform. Ratan Thylam is known for his work in the field of social reform. He is a social activist who has been working for the upliftment of the poor and marginalized people of Manipur. He has also been working for the promotion of education and health in Manipur.