Final answer:
The incorrect set of units is option 4, as it incorrectly lists centimeters as being smaller than micrometers, when it should be the other way around.
Step-by-step explanation:
The set of units that is NOT in the order of increasing size is option 4) cm < μm < km. The correct order should be μm (micrometers) < cm (centimeters) < km (kilometers), as a centimeter is larger than a micrometer but smaller than a kilometer. The other options correctly display units in order of increasing size: option 1) μg (micrograms) < g (grams) < kg (kilograms), option 2) mL (milliliters) < dL (deciliters) < L (liters), option 3) ns (nanoseconds) < ms (milliseconds) < s (seconds), and option 5) μmol (micromoles) < mmol (millimoles) < mol (moles).