Hello. You did not show the passage to which the question refers, which makes it impossible for it to be answered. In the meantime, I will try to help.
Inferences are conclusions that are drawn from reading a text. In this case, it is only possible to answer your question by reading the text, however, we know that these conclusions are related to the behavior of a character called Balto. In this case, we can consider that the behavior of a person can bring conclusions about the personality of that character, about the tension level of a scene, about the tone and mood of a text, about the characterization of another character, about the plot stage and many other things.
The subordinate clause here is A, "as the layers of ash slowly compressed". Subordinate means that it cannot exist on its own, it has to be a part of the main, independent clause.
I would use a venn diagram
