If \(\alpha=\) helix angle, and \(p_{c}=\) circular pitch; then which one of the following correctly expresses the axial pitch of a helical gear?

(a) \(p_{c} \cos \alpha\)

(b) \(\frac{p_{c}}{\cos \alpha}\)

(c) \(\frac{p_{c}}{\tan \alpha}\)

(d) \(p_{c} \sin \alpha\).