Answer:
D. keep your hand and forearm in the same plane
Explanation:
The ergonomic principle explains how to maintain a good posture. And if hands and forearms are in the same plane then you will do least work, and hence not loss more energy, which you can lose if your elbows are close together while typing or your hand and forearm is not in the same plane, or your hands are crossed, or your neck is non aligned to your spines. And if you want to work more efficiently in your office, then you should study ergonomic principles certainly.
