People are confused in their attempts to control malaria in Europe in the early 1900s, because scientists ______.A．identified only one mosquito species instead of six speciesB．thought only three mosquito species transmitted diseaseC．thought there was only

People are confused in their attempts to control malaria in Europe in the early 1900s, because scientists ______.

A．identified only one mosquito species instead of six species

B．thought only three mosquito species transmitted disease

C．thought there was only one mosquito species

D．did not know what species was being studied