Final answer:
One primary rule of firearm safety is to keep firearms unloaded when not in use, which helps prevent accidental discharges and protects both the firearm owner and others. option d
Step-by-step explanation:
One of the four primary rules of firearm safety is to keep the firearm unloaded when not in use. This rule helps to prevent accidental discharges, which can lead to unintended injury or damage. When a firearm is being transported, especially during activities such as climbing a fence or tree, it should be unloaded to ensure safety. Furthermore, following the law which suggests keeping firearms unloaded and secured with a trigger lock or similar device can be a critical aspect of responsible firearm ownership. This rule serves to protect the owner and others from potential harm.
Some of the options listed, such as 'avoid alcoholic beverages during loading,' are also grounded in promoting safety but are not formulated as one of the primary four rules. Additionally, 'always point a loaded firearm at others' and 'keep the firearm loaded at all times' are explicitly against fundamental firearm safety principles. Safety should always be the priority when handling firearms, whether in a laboratory, on the field, or at home.