Who were the first foreign rulers of northwest India in the post-Mauryan period?

Correct answer: Bactrian Greeks

Explanation: The correct answer is D. Bactrian Greeks. After the decline of the Mauryan Empire, a series of foreign invasions began in Northwest India. The Bactrian Greeks (also called Indo-Greeks) were the first among these foreign powers to establish control in the region, around 2nd century BCE. They initially ruled from Bactria (modern Afghanistan) and expanded into northwestern India through the passes of the Hindu Kush. The most famous Indo-Greek king was Menander (Milinda), who is known for his dialogue with the Buddhist monk Nagasena in the text Milinda Panha.