When Juan is "caught... with his guard down," the author means that he wasn't being cautious--not that he physically protected himself most of the time. What tone or attitude toward the character and the audience do the idioms create?

The idioms are creating the way how when you let your guard down many things can happen and in this case Juan having his guard up gave him caution

Explanation:

i believe the answer is: b. mr. head had a long, tube-like face with a rounded open jaw and a short depressed nose.

this is because in the un-revised sentence it said that mr. heads face was long and tube-like, and he had a rounded open jaw. this is not a very grammatically correct because of how it seems to drag on with the and, replaced with, with, makes it sound more fluent in the description.