It tells you that the story is going to be about a secret that the author finally feels that he is ready to reveal it. As a reader, this act as a hook in which makes me interested to find out about his secret.
You can use the synonym clue in understanding the meaning of the underlined word. The other word synonymous to it might be more familiar to you so it would be a lot easier. The synonym clue says the word in a simple way.
I'm guessing that it's "A" because that's the most obvious answer.
However, without having read the entire story, I'm not sure if it isn't "D". You have to look at the context of their relationship to see if maybe Robert is second-guessing himself...and that takes more than a few sentences to determine.
Small jewelry box a strange round metal
Mrs.ellis ( mrs. haney) if this helps