Which sentence uses a verb that agrees with its pronoun subject?

a. Some of the song about the children's games are funny.

b. Both of those cousins studies advance martial arts techniques.

c. Each of us wants to see the new action movie.

d. Someone from electronics store contacted customers for a survey

The first one would be corect, but " some of the song" is not correct, we'd need " some of the songs".

the second needs a verb in plural, so it's also false,

however, both C. and D. are correct. Also Each and someone are both pronouns, so C. and D. both have a subject that agrees with its pronoun subject.