The fog comes on little cat feet. it sits looking over harbor and city on silent haunches and then moves on. what is the main similarity between “fog” and frost’s poem "mending wall"? both use everyday language. both use iambic pentameter. both use strict meter. both use blank verse. (not d or b)

I would say the correct answer is A. Both use everyday language. Both Sandburg and Frost use common, conversational language, without poetic artificialities or any extravagance in form and style. There are no strict rhyme and meter, such as iambic pentameter or blank verse. They communicate their message directly, in an intimate and easily accessible tone.