A long slope is formed in a soil with shear strength parameters$: c’=0$ and $\phi=34^{\circ}$. A firm stratum lies below the slope and it is assumed that the water table may occasionally rise to the surface, with seepage taking place parallel to the slope. Use $\gamma_{sat} = 18 \: kN/m^3$ and $\gamma_u =10 \: kN/m^3$. The maximum slope angle (in degrees) to ensure a factor of safety of $1.5$, assuming a potential failure surface parallel to the slope, would be

- $45.3$
- $44.7$
- $12.3$
- $11.3$