The appropriate answer is doing. decreased atmospheric water vapor leads to an increased greenhouse effect. This is not true because water vapor is a green house gas and increasing the levels of it in the atmosphere will lead to more warming. All the other answers represent appropriate feedback mechanisms associated with global warming.
The correct option is BY CONDUCTING EXPERIMENTS THAT EXPOSE THEIR PROPERTIES.
Scientific investigations are always ongoing in all parts of the world, scientists strive to build on existing knowledge by carrying out more experiments that are targeted at obtaining more information above that which is already known.