The given context has plural subjects, "Sue and Geoff". Thus, plural verb will complement the plural subject.
"Work" in option A is incorrect as here, 'work' is used as a noun and will take a preposition 'in' to be correct.
"Study" in option B does not make sense.
"Run" in option C is correct as the plural subject will take the plural verb 'run' indicates to operate or function.
"Runs" in option D is incorrect as this is used with a singular subject.
Thus, option C is the correct answer.