d
$\mathrm{n}=\frac{1}{2} \sqrt{\frac{\mathrm{T}}{\mathrm{m}}}$
$\therefore \frac{{{n_2}}}{{{n_1}}} = \frac{{{1_1}}}{1}\sqrt {\frac{{{T_2}}}{{{T_1}}}} $
$=\frac{1_{1}}{\left[1_{1}-\frac{40}{100} 1_{1}\right]} \sqrt{\left(\frac{\mathrm{T}_{1}+\frac{44}{100} \mathrm{T}_{1}}{\mathrm{T}_{1}}\right)}$
$=\frac{100}{60} \times \frac{12}{10}=2: 1$