Solution:
Bhim Rao Baba Saheb Ambedkar protested against untouchability. He was highly against such a practice. He also played a crucial role in the writing of the Indian Constitution.
Bhagat Singh did not protest against untouchability. So it is an incorrect option.
Indira Gandhi did not protest against untouchability. So it is an incorrect option.
Therefore, the correct answer is an option (A).
