Milling is the
a. craft of using metal to create different parts, assemble parts together, or create larger structures.
b. process of cutting and shaping unwanted materials or parts to create a desired shape.
c. fabrication method that joins together materials, usually metal.
d. process of making a mold of something; primarily used with bronze metalworking.

Quick using the information in the graph, one might speculate that a) w.w.i created increased job opportunities in the u.s. b) the election of president hoover in 1936 caused unemployment to decline. c) the return of soldiers following w.w.ii caused unemployment to increase in the u.s. d) the new deal programs of president roosevelt created employment opportunities in the u.s.