The Sailendra kings, who had close contact with Indian rulers, were followers of which of the following religions?

The Sailendra dynasty was a prominent ruling family of Southeast Asia (primarily Java and Sumatra) that maintained close diplomatic and cultural relations with Indian rulers like the Palas and Cholas. The Sailendra kings were devout followers of Mahayana Buddhism and are famously known for constructing the magnificent Borobudur Buddhist monument in Central Java.