Who was appointed as the first Surveyor General of India in 1815?

The correct option is Colin Mackenzie.

To understand why this is the correct answer, let's look at the historical context:
Colin Mackenzie (1754–1821) was an administrator, art collector, and renowned cartographer of the British East India Company. He was appointed as the first Surveyor General of India in the year 1815. Under his leadership, extensive surveys of India were conducted, integrating historical and geographical studies to better understand the landscape and administration of the region.

Let's briefly examine why the other options are incorrect:
1. George Michell is a modern-day architectural historian and authority on South Asian architecture, particularly known for his work on Vijayanagara.
2. John Marshall was the Director-General of the Archaeological Survey of India (ASI) from 1902 to 1928, famous for overseeing the excavations of Harappa and Mohenjo-daro.
3. R.E.M. Wheeler was a British archaeologist who served as the Director-General of the Archaeological Survey of India from 1944 to 1948, introducing scientific archaeological methods to India.

Therefore, Colin Mackenzie was the official appointed as the first Surveyor General of India in 1815.