The medium dense sand deposit has a dry unit weight of $16\mathrm{.}5k\frac{N}{m}3,$ a saturated unit weight of $20$

$k\frac{N}{m}3,$ and a fraction angle of $32$ degrees. the function of shear strength is $t_f=c^{\text{'}}+(+a{u}_w)$ tan ${}^{\text{'}}.$

Assume a is equal to $S(S$ is degree of saturation$).$ Calculate the shear strength on a horizontal

plane at depth of $5m$ if the groundwater level is at $6\mathrm{.}5m,$ and the sand is saturated by capillary

action.

a$.97\mathrm{.}22$kPa

b$.60\mathrm{.}75$kPa

c$.125\mathrm{.}37$kPa

d$.20\mathrm{.}90$kPa