An informal tone would be appropriate for
a. a science project presentation.
b. a movie review delivered to friends.
c. a government class debate about a political issue.
d. a presentation to the school principal.

go to crash course lititure and go to seconed page and it shows a video about that

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.)