The pathogen causing filariasis is a type of

Assertion $A$: In elephantiasis, body parts like legs, arms, and genital organs swell significantly.
Reason $R$: In chronic cases, filarial worms block the lymphatic vessels.
Which option is correct for Assertion $A$ and Reason $R$?

Which pathogen causes elephantiasis?

Anti-helminthic drugs like $Mebendazole$ are given to treat . . . . . . .

Which is the correct option for the vector, the infective stage of the pathogen entering the human body, and the location of the pathogen in the vector for elephantiasis?

Match the symptoms of the diseases with their respective causative conditions:
Symptoms of Ascariasis $- P$
Symptoms of Filariasis $- Q$
$I -$ Chronic inflammation of lymphatic vessels
$II -$ Internal bleeding,muscular pain
$III -$ Fever,anemia,and blockage of the intestinal passage
$IV -$ Genital organs are often affected,leading to deformities
$\quad\quad P\quad Q$