The correct answer is (a). Guru Amar Das started the Masand system.
The Masand system was a system of religious administration that was established by Guru Amar Das, the third Sikh Guru. The system was designed to help the Guru connect with his followers and to provide them with religious guidance. Under the Masand system, each village had a Masand, or religious teacher, who was responsible for collecting offerings from the villagers and for teaching them about Sikhism. The Masands also reported back to the Guru on the religious and social conditions in their villages.
The Masand system was a very effective way for the Guru to connect with his followers and to spread the message of Sikhism. The system continued to be used by the Gurus after Guru Amar Das, and it played an important role in the development of Sikhism.
Option (b) is incorrect because Guru Ram Das was the fourth Sikh Guru. He did not start the Masand system.
Option (c) is incorrect because Guru Arjun Dev was the fifth Sikh Guru. He did not start the Masand system.
Option (d) is incorrect because the Masand system was started by Guru Amar Das.