The Figure Below Shows Arcticland's Annual Production Possibilities Boundary for the Production

The figure below shows Arcticland's annual production possibilities boundary for the production of fish and ice. FIGURE 32-4 Refer to Figure 32-4.Starting from point A and moving to point B,the opportunity cost of producing each additional tonne of ice is

A) increasing.
B) increasing followed by decreasing.
C) constant.
D) decreasing.
E) decreasing followed by increasing.