$**$Question:$**$

In civil engineering, when determining the static bearing capacity of piles in clay soil, which soil parameter plays a crucial role in the load$-$carrying capacity of the piles?

$**$a$)$ Shear strength of the soil$**$

$**$b$)$ Permeability of the soil$**$

$**$c$)$ Soil compaction$**$

$**$d$)$ Soil porosity$**$