Which knot can be used as a safety sling while working over the side?

The French bowline is particularly suitable for creating a safety sling while working over the side because it forms a secure loop at its end that does not tighten under load. This characteristic makes it safe and effective for situations where a person might need to be hoisted or secured without the risk of the knot binding or becoming difficult to untie after being used.

When working over the side, having a knot that maintains its integrity and allows for easy release is critical. The French bowline provides a stable loop that can support a person securely, making it a reliable option in safety applications.

The other knots, while useful in various contexts, do not offer the same level of safety or functionality in this particular scenario. For instance, a square knot is primarily used for tying two lines together and may slip under strain, which isn't ideal while working at heights. The sheet bend is good for joining two ropes of different thicknesses, but it doesn’t create a fixed loop. The rolling hitch is excellent for securing a line to a cylindrical object but is not designed to create a reliable loop for safety purposes.