This is a test of commonsense with single/multi-choices. Complete the next sentence:

How to use crutches
Obtain new crutches or used ones that are in very good condition.
Make sure the crutches are sturdy, and that the rubber padding, where your armpit rests, is still springy. Inspect the the bolts or pins that adjust the crutch length.

Pick your answer from:
[I] Place the crutches on your feet and secure them to the hand grips, either with clips or on their pegs using the eyelet. Place the crutches on a controlled foot (such as underhand or ankle slippage or other obstacles)..
[II] Look for crutches that can support your extended range of motion. If you are attempting to walk, you will need to always have crutches and walker styles..
[III] Make sure the crutches have the rubber tips at the bottom. Adjust the crutches to a comfortable height..
[IV] Make sure they are in good working order. Stand tall with the crutches balanced on one foot and your knees bent..
The answer is:
[III]