The correct answer is option 1 - an abnormally warm ocean current.
El Nino is a phenomenon characterized by the warming of the surface waters in the eastern equatorial Pacific Ocean. This warming occurs every few years and disrupts the normal oceanic and atmospheric patterns.
During El Nino, the warm ocean currents move towards the west, and this warming of the ocean affects the global weather patterns. In the case of the South West Monsoon of India, El Nino has a significant impact on the monsoon rainfall.
Normally, during the South West Monsoon, moist air is drawn from the Indian Ocean towards the Indian subcontinent, bringing the much-needed rainfall. However, during El Nino years, the warm ocean currents reduce the temperature contrast between the ocean and the atmosphere, leading to a weakened monsoon. This results in reduced rainfall and sometimes even drought conditions in India.
Therefore, it can be concluded that El Nino, which is an abnormally warm ocean current, is associated with the formation of the South West Monsoon of India.