B) In room 210 there are 3 boys and 17 girls.
Logical fallacies.
These sound correct, but in reality are not.
I would say that the main difference between Sandburg's Fog and Frost's Mending Wall is B. Fog uses everyday language. while Mending Wall does not.
A is incorrect because both poems use metaphors. C is incorrect because both poems are written in free verse. D is incorrect because both poems are written in the modern format.