Most efforts to combat such mosquito-borne like malaria and dengue...

Most efforts to combat such mosquito-borne diseases like malaria and dengue have focused either on the vaccination of humans or on exterminating mosquitoes with pesticides.

A) like malaria and dengue have focused either on the vaccination of humans or on exterminating
B) like malaria and dengue have focused either on vaccinating of humans or on the extermination of
C) as malaria and dengue have focused on either vaccinating humans or on exterminating
D) as malaria and dengue have focused on either vaccinating of humans or on extermination of
E) as malaria and dengue have focused on either vaccinating humans or exterminating

QUESTION: I don’t understand why it the alternative C is wrong.