A flat-head axe's function is to:

The flat-head axe is primarily designed for striking. Its heavy and flat blade allows the user to deliver powerful blows, making it an effective tool in firefighting and rescue situations. This striking capability is used for breaking down doors, walls, and other barriers during emergency operations. The flat surface of the head enables the axe to distribute impact over a larger area compared to a sharp-edged tool, providing greater force when needed, especially in situations where quick access is needed.

While the other options describe actions that can be performed with various tools, they don't specifically reflect the primary function of a flat-head axe. For example, the axe is not primarily intended for cutting as a chainsaw would be; its design does not promote efficient cutting due to its shape. Similarly, although the axe can be used in a manner that involves pushing or pulling, those actions are not its main purpose. The axe might be involved in prying or spreading in some situations, but again, these are not its principal functions.