The correct answer is option 1 - they were interested in Buddhism. Chinese travelers visited India primarily because they had a keen interest in Buddhism, which originated in India. Buddhism had gained popularity in China, and many scholars and monks wanted to study the teachings and scriptures of Buddhism directly from the source. They traveled to India to learn from Indian Buddhist masters and visit significant Buddhist sites. These Chinese pilgrims documented their journeys, which provided crucial information about Indian culture, society, and religious practices. Their writings gave insight into the spread and development of Buddhism in India and its influence on other countries. Therefore, the primary reason for Chinese travelers visiting India was their interest in Buddhism and their desire to deepen their knowledge and understanding of the religion.