Final answer:
The pair of angles that provides a counterexample to the statement: 'If two angles are supplementary, then they form a linear pair' is ∠M = 60 degrees and ∠N = 120 degrees.
Step-by-step explanation:
The pair of angles that provides a counterexample to the statement: 'If two angles are supplementary, then they form a linear pair' is option D. ∠M = 60 degrees and ∠N = 120 degrees.
A linear pair of angles is a pair of adjacent angles whose measures add up to 180 degrees. In option D, the angles ∠M and ∠N are not adjacent, and their measures add up to 180 degrees, but they do not form a straight line, making them an example that counteracts the given statement.
Therefore, option D is the correct answer.