The correct answer is Option 4- Harshavardhana

Hieun Tsang visited India during the reign of Harshavardhana. He was a Chinese Buddhist monk who traveled to India in the 7th century CE to study Buddhism. He spent 17 years in India, and he wrote a detailed account of his travels, which is one of the most important sources of information about India in the 7th century.

Harshavardhana was the ruler of the Indian empire from 606 to 647 CE. He was a powerful and benevolent ruler, and he is remembered for his patronage of Buddhism. Hieun Tsang was impressed by Harshavardhana's rule, and he wrote that he was "a just and merciful ruler, who loved his subjects and protected them from harm."