Best way to answer this problem is to convert all units into SI unit (meter), then compare the output:
0.1 cm = 0.1 x 10^-2 = 1 x 10^-3 m
0.001 m = 1 x 10^-3 m
0.000001 Km = 0.000001 x 10^3 = 1 x 10^-3 m
10 mm = 10 x 10^-3 = 1 x 10^-2 m
1000 µm = 1000 x 10^-6 = 1 x 10^-3 m
Comparing the results, we find that 10 mm is not equal to 0.1 cm.
The answer is (c)