In an experiment of potentiometer for measuring the internal resistance of primary cell a balancing length \[\ell \] is obtained on the potentiometer wire when the cell is open circuit. Now the cell is short circuited by a resistance R. If R is to be equal to the internal resistance of the cell the balancing length on the potentiometer wire will be

• A. \[\ell \]                          
• B. 2 \[\ell \]
• C. \[\ell \] /2                      
• D.        \[\ell \] /4