110. Table 1.3 shows the hypothetical trade-off between different combinations of brushes and combs that might be produced in a year with the limited capacity for Country X, ceterisparibus. Complete the table by calculating the required opportunity costs for brushes and combs.
On the basis of your calculations in Table 1.3, in the production range of 21 to 23 brushes the opportunity cost of producing more comb in terms of brushes is
A. 1/21.
B. 21/23.
C. 1/2.
D. 4.