The figure below shows a graph which qualitatively relates cutting speed at cost per piece produced.
The three curves 1,2 and 3 respectively represent
(a) Machining cost, non-productive cost, tool changing cost
(b) Non-productive cost, machining cost, tool changing cost
(c) Tool changing cost, machining cost, non-productive cost
(d) Tool changing cost, non-productive cost, machining cost