In a experiment for calibration of voltmeter a standard cell of emf 1.5 V is balanced at 300 cm length of potentiometer wire. The P.D across a resistance in the circuit is balancedat 1.25 m. if a voltmeter is connected across the same resistance it reads 0.65 V. the error in the volt meter is
A. 0.5 V
B. 0.025 V
C. 0.05 V
D. 0.25 V