Arrange the following states on the basis of ascending dates of the onset of monsoon : 1. Uttar Pradesh 2. Kerala 3. West Bengal 4. Rajasthan

Answer: Option B

The onset of the monsoon in India typically begins with the arrival of the southwest monsoon over the southernmost state, Kerala, and then progresses northwards.

West Bengal (3): West Bengal, being located in the eastern part of India, usually experiences the onset of the monsoon earlier than states further west or north.

Kerala (2): Kerala, situated in the southern part of India, is usually the first state to experience the onset of the southwest monsoon.

Uttar Pradesh (1): Uttar Pradesh, being located in the northern part of India, typically experiences the onset of monsoon after West Bengal and Kerala but before states further west like Rajasthan.

Rajasthan (4): Rajasthan, being situated in the western part of India, usually experiences the onset of monsoon after other states due to its geographical location.

Therefore, the correct order of the states based on ascending dates of the onset of monsoon is Option B: 3-2-1-4.