Answer:
A. Because humans are much taller than dwarves.
Step-by-step explanation:
1) A beanpole is a stick for supporting beans, according to the dictionary.
2) Beanpole sticks are generally 6-8 feet tall.
3) Context clues: If you do not know what "beanpole" means and don't have access to a dictionary, you can use context clues to help figure out, if not the actual meaning of the unfamiliar word, then at least a small understanding of what it could mean. In this case: "Giant beanpole!" We know that "giant" means big and tall, so we can surmise that "beanpole" is an addition to that descriptive.
4) As an extra assurance, in the passage, there is also "clodhopper" which is a way of saying Maibon is clumsy, but the question does not ask why Doli calls Maibon a clodhopper, so it's safe to assume that A is the correct answer.