When is it illegal to make a right turn on red?

Answer: B — When a "No Turn on Red" sign is posted

Making a right turn on red is a common practice in many states, including Illinois, but there are specific conditions under which this action is prohibited. The presence of a "No Turn on Red" sign clearly indicates that drivers are not permitted to make a right turn at that intersection during a red light, regardless of other circumstances. This rule is in place to enhance safety, ensuring that pedestrians and other road users are protected, and to avoid potential accidents that might occur if a driver ignores this directive. In contrast, turning right on red is generally permitted unless specifically restricted by signage, and the other circumstances described—such as weather conditions or the presence of other vehicles—do not automatically make such a turn illegal. Furthermore, traffic light malfunctions do not pertain directly to prohibitions on turning, as drivers are expected to treat a malfunctioning signal as a four-way stop. Thus, the clear indication from a "No Turn on Red" sign is the definitive reason for prohibiting this action.