Why Is National Defense a Public Good? I

Multiple Choice

Why is national defense a public good? I. because it is expensive to produce II. because people who don't pay for national defense still benefit from having it III. because one person's benefit from national defense doesn't reduce anyone else's benefit from it IV. because it is provided by the government

A) I and IV only
B) II and III only
C) II, III, and IV only
D) I, II, and III only