The correct answer is option 4: Vardhamana Mahavira. Gautama Buddha, also known as Siddhartha Gautama, was the founder of Buddhism. He lived during the 6th and 5th century BCE. Vardhamana Mahavira, on the other hand, was the founder of Jainism and also lived during the same time period as Gautama Buddha.

Now let`s break down the other options to understand why they are not the correct answers:

1. Bhadrabahu: Bhadrabahu was a Jain ascetic who lived in the 3rd century BCE, which is significantly after the time of Gautama Buddha. Therefore, option 1 is incorrect.

2. Chandragupta Maurya: Chandragupta Maurya was the founder of the Mauryan Empire and ruled from 322 to 298 BCE. While he did live during the same time period as Gautama Buddha, he was not a contemporary of him. Option 2 is incorrect.

3. Parsvanatha: Parsvanatha is the 23rd Tirthankara, or spiritual leader, of Jainism. He is believed to have lived during the 9th century BCE, which is much earlier than the