not sure about this one

5, A capacitor is charged to a potential of 20.0 V and is then connected to a voltmeter having an internal resistance of 2.00 MQ. After a time of 6.00 seconds the voltmeter reads 2.00 V. What is the capacitance of the capacitor (in F)? (A) 0.324 (B) D.672 ((C)) 1:30 (D) 0.900 (E) 1.56 (F) 2.18