premise: A police officer on a motorcycle sitting at a traffic light to turn left. hypothesis: They are going to respond to a call.
neutral: A police officer sitting on a motorcycle would not be referred to as 'they', there is no indication that there are multiple people here, it cannot be inferred.  The fact that a police officer is going to turn left does not infer that he is going to respond to a call, he could be on his way to do any number of things.