Final answer:
The tree being described as awesome as an 'artillery piece' is an example of a metaphor, which is a direct comparison without using 'like' or 'as,' used to convey the tree's majesty and power.
Step-by-step explanation:
The question 'Why is the tree described as awesome as an "artillery piece"?' is asking about the type of figurative language used in the description. When a tree is compared to an artillery piece without using the words 'like' or 'as,' it constitutes a metaphor, which is a direct comparison between two unlike things. This analogy conveys the power and majesty of the tree in stark, militaristic terms, likely evoking its size, strength, or the sound it makes in the wind, similar to an artillery piece. It's not a literal description since the tree is not actually a piece of artillery. Therefore, the tree being described as awesome as an 'artillery piece' is an example of a metaphor (option b).