【单选题】Scientists are hoping to eliminate malaria (疟疾) by developing a genetically modified mosquito that cannot transmit the disease. Malaria has long troubled the populations of South America, Africa, and ...
A.
more people have moved to malaria-infected areas
B.
mosquitoes have become resistant to pesticides
C.
genetically modified mosquitoes still transmit the disease
D.
mosquitoes bite as many as 500 million people a year