Which statement is true about this argument?

Premises:

If two angles form a linear pair, then they are supplementary.

If two angles are supplementary, then the sum of their measures is 180∘.

Conclusion:

If two angles form a linear pair, then the sum of their measures is 180∘.


A The argument is valid by the law of detachment.

B The argument is valid by the law of syllogism.

C The argument is not valid because the conclusion does not follow from the premises.

D The argument is not valid because the premises are not true.