Final answer:
In the context of machinery safety, the correct practice is to avoid reaching over the back of the blade to prevent accidental contact and potential injury.
Step-by-step explanation:
While operating machinery with blades such as saws, it is paramount for safety to keep your hands and arms away from the blade. The correct answer is to avoid reaching over the back of the blade. The back of the blade refers to the side opposite to the sharp edge where cutting does not occur. It is the non-functional side of the blade that typically faces the user while the blade is in operation. Reaching over the back can lead to accidental contact with the blade's edge or tip, increasing the risk of injury.