The mood which is established bu the setting, especially in the use of words such as deep, dusk, and black is <em>dark, gloomy, depressing, sad, scary, mysterious, </em>etc.
He probably pointed out that they looked similar because Stryver asked one of the two accusers after being given the note, if he had ever seen someone that looked like Darnay before.
We can infer that it had something to do with their appearance.
And you could have mentioned that this is from "A Tale Of Two Cities"
The answer would be:
<span>Tubman used logos most effectively. She told the group facts about the risks of returning to the plantation, explaining the risks for all involved. She explained that they would have to choose between freedom and death. She wanted them to know that returning wasn't an option.</span>
