Option a is the correct answer. The ancient town of Takshashila, also known as Taxila, was located between the Indus and Jhelum rivers in present-day Pakistan. Takshashila was a center of learning, culture, and trade in ancient India. It was founded by Bharata, the son of Shakuntala and Dushyanta, according to the Mahabharata. It was also associated with Chanakya, the author of Arthashastra. It was visited by Alexander the Great in 326 BCE and later became part of various empires such as the Bactrian Greeks, the Scythians, the Parthians, the Kushans, and the Guptas. Takshashila declined after the invasion of the Huns in the 5 th century CE and was eventually abandoned. It was rediscovered by archaeologists in the 19th century CE and is now a UNESCO World Heritage Site.