You are tailgating if you:

Tailgating occurs when a driver follows another vehicle too closely, reducing the time and distance needed to react to sudden stops or emergencies. The correct answer indicates that if you cannot see the rearview mirrors of the vehicle in front of you, it typically means you are following too closely. This visual reference is essential for maintaining a safe following distance.

Proper following distances allow for adequate reaction time and space to brake safely if the vehicle ahead comes to a stop. A general rule is to maintain at least three seconds of following distance, which is crucial for safety in varied driving conditions.

The other options do not accurately determine whether a driver is tailgating. For instance, being able to see the front of the vehicle ahead does not indicate distance; it could still imply dangerously close proximity. Additionally, having more than one car length between vehicles can often be a safe distance, but it depends on speed and traffic conditions rather than a static measurement. Finally, using a turn signal is unrelated to the concept of tailgating as it pertains solely to signaling intentions while driving.