When a bolt or nut is too tight to loosen with the socket currently being used, which is the safest solution?

Using a larger drive size is considered the safest and most effective solution when a bolt or nut is too tight to loosen. This method provides better leverage and can distribute the force more evenly, reducing the risk of stripping the fastener or damaging the surrounding components. A larger socket also means that more torque can be applied without the risk of breaking tools or injuring oneself.

In contrast, other methods, such as using a monkey wrench, a pipe, or a prybar, can lead to unsafe situations. These methods may not provide adequate grip, can cause damage to the fastener, or result in slips that can cause injury. Thus, opting for a larger drive size is the safe choice for effectively loosening a stuck bolt or nut.