When a resistor of `11 Omega` is connected in series with an electric cell, the current following in it is `0.5 A`. Instead, when a resistor of `5 Omega` is connected to the same electric cell in series, the current increases by `0.4 A` The internal resistance of the cell is
A. `1.5 Omega`
B. `2 Omega`
C. `2.5 Omega`
D. `3.5Omega`
