Which tool is utilized for marking straight lines on footings and walls?

The correct choice for marking straight lines on footings and walls is a chalk line. This tool is specifically designed to create a straight, visible line over long distances. It consists of a string coated with chalk, which, when stretched between two points and snapped, leaves a straight chalk line on the surface, allowing for accurate marking and alignment. This is particularly useful in masonry for ensuring that bricks and blocks are laid out properly, aligning with both aesthetic and structural requirements.

In contrast, a level is used to ensure that a surface is horizontal or vertical, helping to check alignment but not specifically for marking. A bevel square is used for marking and measuring angles, making it more suitable for tasks that require angular measurements rather than straight lines. A trowel is a tool primarily used for applying and spreading mortar, not for marking. Each of these tools serves a distinct purpose, but the chalk line excels in the specific task of marking straight lines.