Assertion: Atoms of different elements always have different atomic masses.
Reason: Atoms of different elements have different chemical properties.
A. Both Assertion and Reason are true, and Reason is the correct explanation of Assertion.
B. Both Assertion and Reason are true, but Reason is not the correct explanation of Assertion.
C. Assertion is true, but Reason is false.
D. Both Assertion and Reason are false.