Relation between optimum cutting speed for minimum cost and maximum production rate

Question

Optimum cutting speed for minimum cost ( V_{c min} ) and optimum cutting speed for maximum production

rate ( V_{r max} )  have which one of the following relationships?

(a) V_c min = V_{r max}                  (b) V_{c min} > V_{r max}

(c) V_{c min} < V_{r max}             (d) V²_{c min =}  V_{r max}