7. Which of the following best explains why research and development expenditures in the construction industry lag behind expenditures in some other countries?

a. U.S. companies see little need to spend money since most competitors are not investing either.

b. Owners and designers tend to be conservative in specifying new products, materials, and methods.

c. New technologies are not time-proven and put the project at risk.

d. It is often difficult to patent or protect from competitors new technologies that are successfully perfected.

e. All of the above are true.