He was a portly, fine-looking gentleman of the old school, with a polished manner, and a certain air of gravity which was very impressive.
Consider the word gravity in the sentence from paragraph 3.

From the four dictionary definitions provided, determine which definition of gravity is LEAST EFFECTIVE as it applies to its use in the sentence.
A) dignity
B) authority
C) significance
D) force toward earth

The sentence is from "The System of Dr. Tarr and Professor Fether by Edgar Allan Poe. This is a description of his character, Monsieur Maillard. The completes sentence is, "He was a portly, fine-looking gentleman of the old school, with a polished manner, and a certain air of gravity, dignity and authority which was very impressive.

In this sentence, the word, gravity means authority and assertiveness.
Option D i.e. force toward earth is the scientific meaning of the force of gravity. It is also an antonym of assertive and authoritative.