The figure below shows a `2.0 V` potentiometer used for the determination of internal resistance of a `2.5 V` cell. The balance point of the cell in the open circuit is 75 cm. When a resistor of `10 Omega` is used in the external circuit of the cell, the balance point shifts to 65 cm length of potentiometer wire. The internal resistance of the cell is
Options:
(a) `2.5 Omega`
(b) `2.0 Omega`
(c) `1.54 Omega`
(d) `1.0 Omega`