Answer:
1. Simile
2. Simile is a literary device that is used to make comparisons between two things using 'like', or 'as'.
3. Steinbeck chose to use this device because he wanted to make analogies or comparisons between some animal and human behaviors.
Step-by-step explanation:
Simile is a way of comparing things directly using 'as' or 'like'. Metaphor makes indirect comparisons by saying that something is another.
Steinbeck used this device in order to compare and contrast certain aspects of the behavior of animals to human behaviors. For example, he contrasted the timidity of the mouse with the braveness of the lion. The squeaking of the muse reveals it's timidity while the roaring of the lion reveals its pride which is the same pride the speaker feels in his profession.