Answer:
A conclusion that is in favour:
"Using public money to maintain national landmarks is a good policy in the sense that a national landmark is a public good: no one can be excluded from enjoying the view of a national landmark like the Arch in St. Louis for example.
Because they are public goods, national landmarks are not likely to be profitable or provided by the private sector in a free market, and for this reason, government intervention in the form of public money becomes necessary".
The correct answer is: C: The sentence has a compound subject. Subject in sentence is<span> the person or thing about whom the statement is made. Every verb in sentence must have at least one subject. But that doesn't mean that it is the only possibility: namely, the verb can have more than one subject, too. In such cases, we can say that a sentence has a compound subject. In this sentence: "Conrad and his sister will sing a duet in the concert.", compound subject is: "Conrad and his sister", since the statement is about the both of them.</span>