The correct answer is: D. Bindusara
Bindusara was the second Mauryan emperor, who ruled from 297 to 272 BCE. He was the son of Chandragupta Maurya and the grandson of Bimbisara. Bindusara was a powerful and successful ruler who expanded the Mauryan Empire to its greatest extent. He was succeeded by his son, Ashoka the Great.
Samudragupta was the third Mauryan emperor, who ruled from 335 to 375 CE. He was the son of Chandragupta II and the grandson of Bindusara. Samudragupta was a powerful and successful ruler who expanded the Mauryan Empire to its greatest extent. He was succeeded by his son, Chandragupta III.
Chandragupta II was the fourth Mauryan emperor, who ruled from 375 to 415 CE. He was the son of Samudragupta and the grandson of Chandragupta I. Chandragupta II was a powerful and successful ruler who expanded the Mauryan Empire to its greatest extent. He was succeeded by his son, Kumaragupta I.
Bimbisara was the first Mauryan emperor, who ruled from 544 to 491 BCE. He was the father of Ajatasatru and the grandfather of Chandragupta Maurya. Bimbisara was a powerful and successful ruler who united the Ganges Valley under his rule. He was succeeded by his son, Ajatasatru.
Therefore, the correct answer is D. Bindusara.