Which of the following factors must be assessed to avoid endangering innocent people when using force?

The necessity to assess whether the suspect poses an immediate threat is fundamental in the use of force, especially in critical situations where innocent lives might be at risk. Evaluating this factor helps ensure that the response is proportional and justified. If a suspect is deemed to be an immediate threat to others or to law enforcement, then the use of force may be deemed necessary to neutralize that threat and protect innocent individuals.

In contrast, while the relative size and strength of individuals involved, the number of witnesses present, and the availability of backup can all influence decision-making in the use of force, they are secondary considerations. These factors can provide context or may support the decision-making process, but they do not directly address the urgency and necessity of the situation at hand. The priority must always be to assess the immediate threat level posed by the suspect, as this directly correlates to the safety of all individuals involved, including innocent bystanders.