The ratio of electron and hole currents in a semiconductor is 7/4 and the ratio of drift velocities of electrons and holes is 5/4, then the ratio of concentrations of electrons and holes will be

5/7 7/5 25/49 49/25

7/5

$I = nAev_d$ or $nv_d$ $∴\frac{I_e}{I_h}=\frac{n_ev_e}{n_hv_h}$ or $\frac{n_e}{n_h}=\frac{I_e}{I_h}×\frac{v_h}{v_e}=\frac{7}{4}×\frac{4}{5}=\frac{7}{5}$