What key elements will be needed for a full four point answer?

1. What is her point?
2. Several reasons the author uses about the trees as a source of strength to keep her keeping.
3. Evaluation of those reasons means making a judgement if her reasons are logical, make sense and there is enough information to support the reasons she states?
4. Discussion of the comparisons and their effectiveness in getting her point across?
5. Of course, examples from the poem to support your ideas and evaluation.

Take your time. If you write all that clearly and completely, you're in for a full four point score!