Multi-choice problem: Continue writing the next sentence in this paragraph:

How to improve your posture at work
Adjust your chair height so your forearms line up with your keyboard.
Having to reach up or down with your arms when you're typing is bad for your posture. To have good posture at your desk, raise or lower your chair until your forearms are at the same height as your keyboard when you're typing.

OPTIONS:
[I] Put about 5 mm of noise in between your word and keyboard height. Try to put a sound between your words.
[II] This means that your arms should be at a 45 degree angle to your desk, and your elbows should be at a 90 degree angle. Lower yourself to the point that your toes can touch the desk.
[III] Try to form a 90-degree angle with your elbows. Most office chairs have a lever or knob underneath them that you can use to adjust their height.
[IV] Then, pull your elbows in and lean in. You'll need to repeat the movement in various ways.
[III]