In their calculation, concentration ratios take barriers to entry into a market into consideration

Since 1945, national defense expenditures as a percentage of GDP have _____

a. fallen from 41 percent to 3.7 percent b. fallen from 32.1 percent to 20.1 percent c. fallen from 62.3 percent to 11.5 percent d. fallen from 50.5 percent to 9.6 percent

A person's utility schedule ____________ (can/cannot) change over time.

Fill in the blank(s) with the appropriate word(s).