Evenness means an equality between two species, or to sets of variables in mathematics, so evenness of mind and temper would be a tranquility or peace between these two parts of your body.
A ten letter word with this meaning is Equanimity.
Definition: mental calmness, composure, and evenness of temper, especially in a difficult situation.
The obvious answer would be C. rhyme.
As you can see, each of these lines rhyme: sea rhymes with C, and me, and be. Those words sound similar, which means they rhyme. There are no metaphors (comparisons) and onomatopoeias (mimicking the sounds from nature) here, or alliterations (repetition of the same consonant) in this excerpt.
