The South West monsoon is a seasonal weather phenomenon that brings rain to the Indian subcontinent. According to the provided options, the correct answer is option 4, which states that the entire India is engulfed by the South West monsoon on 15th July.

Option 1 states that the monsoon engulfs the entire India on 5th June. However, this is incorrect as the monsoon typically arrives later in India.

Option 2 states that the monsoon engulfs the entire India on 15th June. This is also incorrect as the monsoon usually takes a few more weeks to cover the entire country.

Option 3 states that the monsoon engulfs the entire India on 1st July. This is incorrect as well, as the monsoon typically arrives later in July.

Therefore, the correct answer is option 4 – 15th July.