The correct answer is: c) Post-Mauryan and early Gupta period.
The Buddhist ruins in Arunachal Pradesh are evidence of the spread of Buddhism to the region during the Post-Mauryan and early Gupta period. The Mauryan Empire was a powerful empire that ruled over much of India from the 4th to the 2nd century BCE. During this time, Buddhism was the state religion of the empire and spread widely throughout India. After the fall of the Mauryan Empire, Buddhism continued to spread, and the early Gupta period (320-550 CE) was a time of great Buddhist expansion. During this time, many Buddhist monasteries were built in Arunachal Pradesh, and the region became a major center of Buddhist learning and culture.
The Vedic Age was a time of great religious and cultural development in India. The Vedas are a collection of sacred texts that are considered to be the foundation of Hinduism. The Vedic Age is generally thought to have lasted from around 1500 to 500 BCE. During this time, Buddhism did not exist as a separate religion.
The Pre-Mauryan period was a time of political and social upheaval in India. The Mauryan Empire was not yet established, and there were many different kingdoms and empires vying for power. During this time, Buddhism was still a relatively new religion, and it did not have a strong presence in Arunachal Pradesh.
The Medieval period was a time of great change and upheaval in India. The Gupta Empire had fallen, and the region was divided into many different kingdoms. During this time, Buddhism continued to decline in popularity, and Hinduism became the dominant religion in India.
In conclusion, the presence of Buddhist ruins in Arunachal Pradesh suggests the influence of Buddhism during the Post-Mauryan and early Gupta period.