Which of the following was the capital of Mahajanapada Gandhara in 6th century BC?

Taxila

The correct answer is Option 3- Taxila

The capital of Gandhara in the 6th century BC was Taxila. It was a major center of learning and culture, and was known for its university, which attracted scholars from all over the world.

Gandhara was one of the sixteen Mahajanapadas, which were large kingdoms that existed in India during the Iron Age. It was located in the northwest of India, in the present-day region of Khyber Pakhtunkhwa in Pakistan.

Taxila was a strategic location, as it was on the trade route between India and Central Asia. It was also a major center of Buddhism, and was home to many Buddhist monasteries and stupas.