What creates a pressure differential during the drafting process?

During the drafting process, a pressure differential is created when air is pumped out of the intake hose. This process is critical because it lowers the air pressure within the hose, allowing atmospheric pressure outside the hose to push water up into the hose from the source, such as a body of water.

When the pump operates, it generates a vacuum effect by removing air, which results in lower pressure inside the intake hose compared to the atmospheric pressure outside. This difference in pressure enables water to be drawn up from a lower elevation, making it essential for effectively drafting water from sources like ponds or lakes.

Understanding this principle is crucial for driver engineers, as it directly impacts their ability to perform effective drafting operations in firefighting scenarios. The other options do not directly contribute to the creation of a pressure differential needed for drafting.