Which answer contains a proper in-text citation?

a. According to Middlebrook, swimming is unlike other sports because "it uses several different muscle groups (55)."

b. Swimming is unlike other sports because "it uses several different muscle groups" (Middlebrook 55).

c. According to Middlebrook, swimming is unlike other sports because "it uses several different muscle groups." (Middlebrook 55)

d. Swimming is unlike other sports because it uses several different muscle groups, says Middlebrook.
please i need this answer quick :)