Answer: (Detailed Solution Below)
Option A: Arya Samaj
Detailed Solution:
The correct answer is “Arya Samaj”.
The Arya Samaj started the Shuddhi movement in the early 20th century to reconvert Hindus who had converted to Christianity or Islam. The movement's founder was Swami Dayanand Saraswati, along with his friend and follower Swami Shraddhanand.