Explanation:

- Option 1: Jaipur

- Jaipur, the capital of Rajasthan, is known for its historical and cultural significance, but it is not the location of a major solar observatory.

- Option 2: Udaipur

- Udaipur is home to the Udaipur Solar Observatory.

- This observatory is located on an island in Fatehsagar Lake, providing good conditions for solar observations due to its strategic location.

- It is one of the best solar observing sites in Asia.

- Option 3: Kota

- Kota is a major city in Rajasthan but does not host a prominent solar observatory.

- Option 4: Ajmer

- Ajmer is a historic city in Rajasthan but is not known for hosting a solar observatory.

Your pick, Option 2: Udaipur, is indeed correct.