What is the denotation of the word childhood?

Youth, because that is what you are basically saying when referring to you childhood. In your youth or childhood you are talking about the past as a young girl/boy.

what are the phrases to choose from?

the sentence that best describes the tone of the passage from the radio broadcast compared to the passage from the book is b. the radio broadcast has a more surprised tone.

consider the text evidence: in the passage from the book, the description is more matter-of-fact. it is simply describing the things resembling little grey snakes, but there is no urgency in the description. on the other hand, in the passage from the radio broadcast, there is definetely urgency (you can tell from the expression used, "good heavens", which clearly indicates surprise.)