The coefficient of static friction is always 

The coefficient of static friction is always greater than or equal to 0

A) The coefficient of static friction

${\mu }_{\text{s}}=\frac{{\text{f}}_{\text{s}}}{\text{N}};{\mu }_{\text{s}}\ge 0$

${\mu }_{\text{s}}$ is a ratio have no $-\text{ve}$ values