I'll give you a question, please answer with step-by-step reasoning process.
If someone had been smoking, an easy way to tell would be if they were what?\nOptions:\n- inhale\n- unhealthy\n- a chimney\n- go outside\n- coughing

coughing
Someone might be coughing if they are smoking.

If someone had been smoking, an easy way to tell would be if they were coughing.

.

So, the final answer is coughing