What does print(sorted(a | b)) print? Python Dictionaries, Sets and Comprehensions

Answer, C. [1, 2, 3, 4, 5]

A. [1, 2, 3, 3, 4, 5]

Assumes the shared element 3 appears twice in the union because it exists in both sets. A set can never hold a duplicate value, an element that belongs to both operands still appears only once in the union.

B. [3]

Assumes | computes the intersection of the two sets instead of their union. The | operator is set union, it combines every element from both sets, the shared element 3 is not the only thing kept.

C. [1, 2, 3, 4, 5]

Correct. The union operator combines every distinct element from both sets, giving all of 1 through 5 once each, since 3 is shared it still only appears a single time.

D. [1, 2]

Assumes union keeps only the elements unique to the first set, similar to a difference operation. Union keeps every element present in either set, elements from b, like 4 and 5, are included too.

The | operator on two sets returns their union, a new set containing every element that appears in either operand, with duplicates naturally collapsed since a set cannot hold the same value twice. sorted() is used here only to get a deterministic printable order, it does not change which elements are present.