Which of the following is the correct expression of K_f which depends upon the nature of solvent?

$\displaystyle \mathrm{K}_{\mathrm{f}}=\frac{\mathrm{M}_{1} \times \mathrm{T}_{\mathrm{f}}^{2}}{\mathrm{R} \times 1000 \times \Delta_{\text {fus }} \mathrm{H}}$

$\displaystyle \mathrm{K}_{\mathrm{f}}=\frac{\mathrm{R} \times \mathrm{M}_{1} \times \Delta_{\text {fus }} \mathrm{H}}{1000 \times \mathrm{T}_{\mathrm{f}}^{2}}$

$\displaystyle \mathrm{K}_{\mathrm{f}}=\frac{\mathrm{R} \times \mathrm{T}_{\mathrm{f}}^{2} \times \Delta_{\text {fus }} \mathrm{H}}{1000 \times \mathrm{M}_{1}}$

$\displaystyle \mathrm{K}_{\mathrm{f}}=\frac{\mathrm{R} \times \mathrm{M}_{1} \times \mathrm{T}_{\mathrm{f}}^{2}}{1000 \times \Delta_{\text {fus }} \mathrm{H}}$