The correct answer is (a) Tirupati.
Tirupati is a city in the Indian state of Andhra Pradesh. It is one of the most popular pilgrimage sites in India, and is home to the Venkateswara Temple, which is dedicated to the Hindu god Vishnu. The temple is one of the richest temples in the world, and is visited by millions of pilgrims every year.
Amarnath is a cave shrine in the Indian state of Jammu and Kashmir. It is one of the most popular pilgrimage sites in India, and is dedicated to the Hindu god Shiva. The cave is located in the Himalayas, and is only accessible during the summer months.
Varanasi is a city in the Indian state of Uttar Pradesh. It is one of the oldest cities in the world, and is one of the most important pilgrimage sites in Hinduism. The city is home to the Kashi Vishwanath Temple, which is dedicated to the Hindu god Shiva.
Rishikesh is a city in the Indian state of Uttarakhand. It is a popular destination for Hindu pilgrims, and is home to a number of temples and ashrams. The city is also known for its yoga and meditation retreats.
In conclusion, the most visited pilgrimage site in Andhra Pradesh is Tirupati.