5. A uniform meter stick has a 45.0g mass placed at the 20cm mark as shown in the figure. If a pivot is placed at the 42.5cm mark and the meter stick remains horizontal in static equilibrium, what is the mass of the meter stick?
(A) 45.0 g
(B) 72.0 g
(C) 120.0 g
(D) 135.0 g