Final answer:
The question is about safe handling of equipment loads, for which the correct answer is 'secure.' Ensuring loads are both secure and balanced is critical for safety.
Step-by-step explanation:
The question pertains to ensuring the safety and stability of loads being carried by equipment. The most appropriate word to complete the sentence 'Make sure all loads carried by equipment are stable and ______' is secure. When loads are secure, it means they are firmly fixed and not likely to move or fall, reducing the risk of accidents or damage.
A load that is balanced is equally important, as uneven loads can cause equipment to tip over or operate inefficiently, leading to potential safety hazards. Although 'efficient' and 'reliable' are positive attributes, they do not directly address the immediate physical safety concern about a load's potential movement or shifting during transport or operation.