From the ¨Lumber-room ( Its a story) How do the words stealth, evade, and sentry-duty in paragraph 6 impact the tone of the passage?

They emphasize the conflict and unstated competition between Nicholas and his aunt.

They emphasize the inexperience Nicholas displays in developing a plan to deceive his aunt.

They emphasize the unkind nature of the aunt in her interactions with Nicholas and his cousins.

They emphasize the contest Nicholas and his aunt will engage in while the cousins are out.
This is paragraph 6 Nicholas made one or two sorties2 into the front garden, wriggling his way with obvious stealth of purpose towards one or other of the doors, but never able for a moment to evade the aunt’s watchful eye. As a matter of fact, he had no intention of trying to get into the gooseberry garden, but it was extremely convenient for him that his aunt should believe that he had; it was a belief that would keep her on self-imposed sentry-duty for the greater part of the afternoon. Having thoroughly confirmed and fortified her suspicions, Nicholas slipped back into the house and rapidly put into execution a plan of action that had long germinated3 in his brain. By standing on a chair in the library one could reach a shelf on which reposed a fat, important-looking key. The key was as important as it looked; it was the instrument which kept the mysteries of the lumber-room secure from unauthorized intrusion, which opened a way only for aunts and such-like privileged persons. Nicholas had not had much experience of the art of fitting keys into keyholes and turning locks, but for some days past he had practiced with the key of the schoolroom door; he did not believe in trusting too much to luck and accident. The key turned stiffly in the lock, but it turned. The door opened, and Nicholas was in an unknown land, compared with which the gooseberry garden was a stale delight, a mere material pleasure.