Name the first site from where the Indus Valley Civilization was discovered.

The correct option is Harappa.

The Indus Valley Civilization is also popularly known as the Harappan Civilization because Harappa was the very first site of this ancient civilization to be discovered and excavated.
In 1921, the Archaeological Survey of India (ASI), led by Indian archaeologist Daya Ram Sahni under the supervision of Sir John Marshall, began excavations at Harappa (located in present-day Punjab, Pakistan). This historic discovery revealed the existence of a highly advanced Bronze Age urban civilization, pushing back the known history of the Indian subcontinent by thousands of years.

Here is a brief overview of the other options to understand their context:
• Rakhigarhi: Located in Haryana, India, Rakhigarhi is one of the largest known sites of the Indus Valley Civilization, but excavations here began much later, in the late 1990s.
• Hulas: Located in Uttar Pradesh, India, Hulas is a Late Harappan site discovered and excavated in the latter half of the 20th century.
• Sinauli: Located in Uttar Pradesh, India, Sinauli is famous for its significant archaeological finds including solid-disk wheel chariots and copper-hoard burials, but these excavations took place recently in the 21st century (starting in 2005).