pls help quickly <3 In which sentence is a semicolon used correctly?

a.The documentary about Einstein was informative; I plan to ride my bike on Tuesday.
b.They met at the restaurant before prom; they didn’t want to be hungry at the dance.
c.The music played soulfully through the building; and the employees danced.
d.Because the football game would be crowded; we left an hour early for the stadium.