The Figure Depicts a Shift in a Society's Production Possibilities

Multiple Choice

The figure depicts a shift in a society's production possibilities frontier (PPF) for the manufacture of trains and planes: train-manufacturing capacity expands while plane-manufacturing capacity shrinks. Refer to this figure to answer the following questions.

-Which point represents an efficient level of output both before and after the shift?

A) point A
B) point B
C) point C
D) point D
E) point E