The correct option is B Proboscis
The mosquitoes are dioecious. The mosquito's proboscis, is a long needle-like antenna that extends from the area of its mouth, is the best indicator of the insect's gender.
Male mosquitoes have a feather-like proboscis, while the proboscis of the female is relatively smooth, not bushy. The hair on the antenna is called as antennal flagellum
So, the correct answer is option B.