The Gupta era was started by Srigupta. Option 1, Ghatotkacha, is not correct as he was a character from the Mahabharata and not associated with the Gupta era. Option 3, Chandragupta, is not correct as he was the founder of the Maurya Empire and not the Gupta era. Option 4, Samudragupta, is not correct as he was a later ruler of the Gupta dynasty, known for his military conquests and patronage of the arts. Therefore, the correct answer is option 2, Srigupta. He was the founder of the Gupta dynasty and his reign marked the beginning of the Gupta era, which is considered a golden age in ancient Indian history.