#53 was pretty nebulous.
Answer could have just as easily been A
Yes, that was my problem too. I think they were looking for a very pedantic definitiion of ‘public good’ from classic economics.
The other one I got wrong, I misread one of the possible answers.
A public good is a good that can be enjoyed by me without reducing the supply of it potentially available to you, i.e., a good we don't have to contend over. None of the answers address the definition. You can quickly eliminate all but B, but B isn't very satisfying as an answer.
National defense is certainly a public good, and it's true that Mr. Bill pays a lot for his, I pay some, and the homeless guy nothing. But the fact that the homeless guy gets defended for nothing isn't material to the definition.