A controlled railroad crossing is identified by a STOP sign. flashing red lights and a crossing gate. listening for the warning sound from the train. yellow lights over the crossing.

## Step 1<br />A controlled railroad crossing is a type of railroad crossing that has some form of control to warn drivers when a train is approaching. This control can be in the form of a signal, a crossing gate, or a warning sign.<br /><br />## Step 2<br />The options provided in the question are:<br />- a STOP sign<br />- flashing red lights and a crossing gate<br />- listening for the warning sound from the train<br />- yellow lights over the crossing<br /><br />## Step 3<br />Among these options, the one that best represents a controlled railroad crossing is "flashing red lights and a crossing gate". This is because these are the most common forms of control used at railroad crossings.<br /><br />## Step 4<br />The other options, such as a STOP sign, listening for the warning sound from the train, and yellow lights over the crossing, are not as common or reliable as flashing red lights and a crossing gate.