A force ' \(F\) ' is to be transmitted through a square threaded power screw into a nut. If ' \(t\) ' is the height of the nut and ' \(d\) ' is the minor diameter, then which one of the following is the average shear stress over the screw thread?

(a) \(\frac{2 F}{\pi \mathrm{d} t}\)

(b) \(\frac{F}{\pi \mathrm{d} t}\)

(c) \(\frac{F}{2 \pi \mathrm{d} t}\)

(d) \(\frac{4 F}{\pi \mathrm{d} t}\).