The document defines sets a, b, and c as collections of numbers. It finds the union of sets a and b, which is the combination of all numbers in both sets. It then finds the intersection of the union of a and b with set c. The intersection contains elements that are common to both sets. However, there are no common elements between the union of a and b ({1, 3, 5, 7, 9, 11}) and c ({2, 4, 6, 8}). Therefore, the result is an empty set, which is not one of the answer choices given. The answer is D. none of these.