Select the most appropriate set of words from the given choices to fill in the blanks.

Our Constitution was based on the belief that the free ___________ of ideas, people and cultures is essential to the ___________ of a democratic society.

A. selection, concurrence

B. interchange, preservation

C. reversal, upholding

D. dissemination, congruence

Please do not use chat terms. Example: avoid using "grt" instead of "great".