The correct option is A Elephantiasis
Elephantiasis is caused by a worm, Wuchereria bancrofti. It is transmitted by female Culex mosquito. The disease is characterised by the swelling of legs and scrotum.
On the other hand, ascariasis is caused by Ascariasis lumbricoides, ringworm is caused by Trichophyton mentagrophytes and kala - azar is caused by Leishmania donovani.