Volunteer fire departments primarily depend on their members to respond to emergencies when?

Volunteer fire departments primarily depend on their members to respond to emergencies because many of these departments are not continuously staffed. Unlike career fire departments that maintain a full-time presence at the station, volunteer departments operate with available personnel who may have other jobs or commitments. Therefore, the willingness and ability of individual volunteers to respond when needed become crucial. This reliance on volunteers to be available during emergencies ensures that the department can function effectively, even if they cannot guarantee full staffing at all times.

The other options do not accurately reflect the operational reality of volunteer fire departments; casual or scheduled responses do not account for the necessity of immediate availability during emergencies.