Which word in the sentence does the adjective clause modify?

my mother's father, who once explored the north pole, is still active.

a.
father

b.
explored

c.
mother's

d.
active

situational archetype describes the adventures of hero. the examples of situational archetypes are the quest, good vs evil, the task which represent respectively search, good forces, characters vs the evil ones and a certain job that must be done. from the given options, we cannot observe the subplot the beauty and the beast which is a correct answer for this question.

is it multiple