Figure 2-7 -Which of the Following Could Explain the Shift in the the Shift

Figure 2-7

-Which of the following could explain the shift in the production possibilities frontier from AB to AC in Figure 2-7?

A) a productive improvement in petroleum production that has no effect on clothing production
B) a productive improvement in clothing production that has no effect on petroleum production
C) an increase in the size of the labor force that can produce either petroleum products or clothing
D) oil drilling in Alaska is ended in order to protect the environment
E) major oil reserves are discovered off the coast of Africa