Final answer:
The period from December 1969 through November 1973 was an expansion.
Step-by-step explanation:
An expansion in the context of U.S. economic activity refers to a period of economic growth and increasing real GDP. To determine the period of expansion, we need to identify the dates of successive turning points and compare the levels of real GDP at those times. From the given data, the turning points are as follows:
(A) Feb. 1961 2352.9
(B) Dec. 1969 3571.4
(C) Nov. 1973 3566.5
(D) Nov. 1973 4151.1
(E) Mar. 1975 4010.0
Based on these turning points and real GDP levels, we can conclude that the period from December 1969 through November 1973 was an expansion because real GDP increased from 3571.4 in December 1969 to 4151.1 in November 1973.