According to the Text There Appear to Be Very Limited

Multiple Choice

According to the text there appear to be very limited opportunities for input substitution in the production of pipe organs.Which of the following is the most plausible explanation for this observation?

A) Capital costs have made it too expensive to purchase more capital stock.
B) It requires a large amount of highly trained labor to produce a single pipe organ.
C) The marginal productivity of additional trained workers is zero.
D) The capital used in producing pipe organs is much more expensive than the labor inputs.