Final answer:
When firing a rifle, you should hold your breath after taking a deep breath to minimize body movement and increase accuracy. The chest muscles work to expand the lungs during this process.
Step-by-step explanation:
When you're ready to fire a rifle, after drawing a deep breath, the recommended action is A) Hold your breath. This is because holding your breath stabilizes your body and minimizes movement, allowing for greater precision when aiming and firing the weapon. When taking a deep breath, the muscles in your chest are actively working to expand your lungs, thereby allowing them to fill with air. This control over your breathing is critical in achieving accuracy when shooting.