Malaria can be prevented by:

The correct option is D using mosquito nets
$\bullet$ Malaria is caused by parasites and is spread by mosquitoes.
$\bullet$ We can prevent malaria by protecting ourselves from a mosquito bite.
$\bullet$ Mosquito lay eggs in still water. Hence, stagnent water places should be cleaned regularly.
$\bullet$ By using mosquito repellent creams, nets and wearing clothes, we can limit the contact of mosquitoes with humans.