Which of the following markets is most likely to be oligopolistic?

The greater the magnitude of the external benefits of production, a. The larger is the deadweight loss from underproduction

b. The greater would be the optimal subsidy. c. The further the private market solution ignoring those benefits would deviate from the socially efficient level of output. d. All of the above are true

If investment is zero, the capital stock

A. continues to flow. B. falls to zero. C. remains constant. D. grows steadily.