The correct answer is A. Peaceful
Step-by-step explanation:
In the excerpt presented, the atmosphere or mood can be described as peaceful, this mood is created through the setting that is a comfortable train moving smoothly "the soft cushions enfolding his head in an easy embrace. The motion of the train slowly rocked him" and reinforced by the attitude of the character that sits in the train and it is so relaxed that he decides to sleep "providing the perfect background for sleep"; besides this, details such as "A slight breeze from an open window" or "the warmth of the car covered him" show the reader all the elements in this scene are calmed creating a peaceful or tranquil mood.