Explanation:

Gautama Buddha, the founder of Buddhism, and Vardhaman Mahavira (Option D), the 24th and last Tirthankara of Jainism, were contemporaries. Both lived in the 6th century BCE and propagated their respective philosophies in ancient India. Bhadrabahu (Option A) was a Jain monk who lived later, during the time of Chandragupta Maurya (Option B), who founded the Mauryan Empire in the 4th century BCE, well after Buddha and Mahavira. Parsvanath (Option C) was the 23rd Tirthankara, preceding Mahavira.