Guys pls answer this question for me pls

pouring a layer of oil in water

Explanation:

hope this helps you

I think the answer is washing vegetables before cooking them.because this will definitely cause cholera and not malaria.(D)

but if you use the other methods on a,b and c they can stop the spread of malaria.for example if you pour oil on the surface of water it can prevent mosquitoes from breeding or cause death to the eggs,thereby preventing malaria same applies to b and c.

I hope this helps

the correct answer is c   with the systems