After how long will the red light turn OFF if it is on after the float switch closes?

The correct choice indicates that the red light will turn off after 1.5 hours following the closure of the float switch. This duration is significant in the context of systems involving float switches, which are commonly used for water level regulation in various applications, such as sump pumps or aquariums.

When the float switch closes due to the water level reaching a certain point, it typically triggers an action, such as turning on a pump or an indicator light (like the red light). The duration for which the light remains on often correlates with a specific operational timeframe designed to allow for adequate responses to changing conditions.

In certain systems, a prolonged indication (like 1.5 hours) serves a functional purpose, such as alerting users about ongoing processes or ensuring that equipment remains active during a certain period without interruption. This timeframe might be crucial for maintaining systems or providing sufficient time for an operator to intervene if necessary.

Other durations like 30 seconds, 1 minute, or 90 seconds may not provide enough time for certain operations or alerts that would be critical in practical scenarios, such as allowing a pump to operate or indicating a fault condition adequately. Therefore, the extended period of 1.5 hours is the most precise approach for ensuring