This test that albert chong and his colleagues carried out was most relevant for evaluating the
a. productive efficiency of these postal services because the test was designed to measure how much it cost to send and return letters in various countries.
b. allocative efficiency of these postal services because the test was designed to measure how often and how quickly the letters sent were returned.
c. allocative efficiency of these postal services because the test was designed to measure how much it cost to send and return letters in various countries.
d. productive efficiency of these postal services because the test was designed to measure how often and how quickly the letters sent were returned.