An earthen dam of height $H$ is made of cohesive soil whose cohesion and unit weight arc $c$ and $\gamma$ respectively. If the factor of safety against cohesion is $F_c$, the Taylor’s stability number $(S_n)$ is

1. $\dfrac{\gamma H}{cF_c} \\$
2. $\dfrac{cF_c}{\gamma H} \\$
3. $\dfrac{c}{F_c \gamma H} \\$
4. $\dfrac{F_c \gamma H}{c}$