The correct answer is: A) The word “buying” should be in quotation marks because it is an ironic use: Parker wasn’t authorized to sell those landmarks, and the people who gave him money didn’t really buy anything.
In this case scare quotes are being used to distance from the word "buying", either because it is odd or inappropiate. In this case it is used to express irony.
The people paying for the Brookyn Bridge or the Statue of the Liberty thought they were doing a real deal but they were being scammed. For them, it was all a real transaction in which they had to pay in exchange for a product. For George C. Parker and us that know the real story, they were not buying anything, that is why the quotes are used.