The correct option is B an aristocrat
Blue blood means a person of noble birth.
Hence option B is the correct answer because an “aristocrat” is a member of an aristocracy which means the highest class in certain societies, typically comprising people of noble birth holding hereditary titles and offices.
Hence option B is the correct meaning of the given idiom.
Option A is incorrect because something impossible means something that cannot be done.
Option C is incorrect because something costly is something very expensive and has a high price.
Option D is incorrect because a funny object is any object that looks or sounds or makes people laugh. Hence the other three options are incorrect.