The choice of the words "grave" and "solemn" suggests that the people involved in the trial are treating the proceedings with deep seriousness and a sense of heavy responsibility. This indicates that they understand the weight of the situation, particularly given the dire consequences that accusations of witchcraft could have on individuals and the community at large. The emphasis on seriousness reflects the tension and fear prevalent in the society, underlining the gravity of the accusations and the potential repercussions for those accused. Therefore, the most fitting response would be:
The words refer to how seriously the people are taking the proceedings of the trial.