Question Detail
Question
Which of the following is always true?
Correct Answer
Option D is the correct answer.
Detailed Explanation
A ∪ A = A is always true. A ∩ A = A is also true, but that's option A. Both A and D are true. However, option A is A ∩ A = A, which is correct. Option D is A ∪ A = A, also correct. The question says "always true", and both are true. Possibly only one is listed as correct. Option A is standard.
Hint
Recall basic set identities: idempotent laws.