Answer : 4. "Monsoon experiment"
Explanation :

Answer: D) Monsoon experiment Explanation: Monsoon experiment is abbreviated as MONEX.   The Monsoon Experiment is the core of the GARP Monsoon Subprogramme, which is a major international effort to achieve a better understanding of the Planetary monsoon circulation, the major seasonal perturbation of the general circulation of the atmosphere and the influence of the annual cycle of precipitation associated with the monsoon on the agriculture of the many populous nations of the region.   Hence, MONEX is associated with The Monsoon Experiment.