What defines a "sluggish" oxygen sensor?

A "sluggish" oxygen sensor is typically defined by its slower response to changes in exhaust gas composition. This sluggish behavior can indicate that the sensor is not functioning optimally, and one of the potential reasons for this impairment is contamination. Contaminants such as oil, antifreeze, or excessive carbon buildup can affect the sensor's ability to accurately read the oxygen levels in the exhaust, leading to delayed responses. This can negatively impact the engine's air-fuel mixture settings, hence affecting performance and emissions. While other options touch on aspects of oxygen sensor performance, they do not directly relate to the operation of a sluggish sensor, making contamination the most relevant choice in this context.