If the Habakkuk thesis had been correct—unamended by Rosenberg, Davi

If the Habakkuk thesis had been correct—unamended by Rosenberg, David and others—a long-run decline in the supply of agricultural productivity west of the Appalachians would be matched by a proportional

(a) decline in the productivity growth in eastern manufacturing.
(b) increase in productivity in eastern manufacturing.
(c) rise in American food imports.
(d) rise in American exports of manufacturing.

ANSWER

(a)