The measures that can be taken to control the global warming

The correct option is A All of the above
Global warming
Since global warming makes the climatic changes of the Earth, it is a global concern and hence collective measures should be taken internationally.

Planting trees
Planting trees would help to increase oxygen concentration in the atmosphere. Also, this would increase the consumption of $C{O}_2$, a greenhouse gas, in photosynthesis.

Human population
Reducing the growing population can help minimise the pollution from various anthropogenic actions. And eventually, the concentration of greenhouse gases in the atmosphere will reduce and be normalised, which would in turn control global warming.

International initiatives
International initiatives like the Kyoto Protocol, Rio Earth Summit, etc. have also been taken to control global warming.

Final answer
(d) All of the above