Which of the following often involves positive external benefits?

Use the NBER data in Table 8.1 in the textbook on U.S. business cycle turning points to calculate:

a) the shortest business cycle from peak to peak; b) the shortest business cycle from trough to trough; c) the longest business cycle from peak to peak; and d) the longest business cycle from trough to trough.

Mary says she plans to return to college next semester assuming her car keeps running, tuition fees don't go up, and she will still have a student loan. An economist would say that Mary plans to return to college next semester

A) caveat emptor. B) ceteris paribus. C) laissez faire. D) post hoc ergo propter hoc