The correct option is
C The masses cannot be expected to appreciate what only a few, intelligent people can.
"Democratize" means to make anything available or accessible to all the masses or all kinds of people in public.
The author says that high art will not be taken in positively by all types of people because various types of people have various types of exposure to different parts of the society, and not everyone can understand or appreciate high art, hence Option C is the correct answer.
Option A is incorrect because "sublimate" means todivert or modify anything into a culturally higher or socially more acceptable activity, which means that high art can easily be diverted, which is incorrect because any form of art cannot be influenced.
Option B is incorrect because it might be true that people differ in their emotional experiences, but emotions cannot be related to art, as in, art cannot be influenced by emotions.
Option D is incorrect because "to improvise" means to produce or make (something) from whatever is available, which should not be a necessity for people to be able to accept the form of high art, hence it is incorrect.