Suppose U = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10} is the universal set and M= {7, 8, 9,10). What is M'?

A: {1, 2, 3, 4, 5, 6,}

B: {1, 2, 3, 4, 5, 6, 7, 8, 9, 10}

C: cannot be determined

D: {7, 8, 9, 10}