One Reason That Investment in Innovation Is Often Considered to Have

One reason that investment in innovation is often considered to have increasing marginal returns is because

A) new products increase firms' profits.
B) R&D costs are negligible relative to firms' total costs.
C) innovation is mostly through "leaning by doing."
D) new ideas or innovations can spawn ever further new ideas and innovations.
E) after the initial investment is made,subsequent investors face more difficult and expensive production problems.