Answer:
OPTION A; Emma claimed responsibility for the WELL-PLACED American flag.
Explanation:
Hyphen is used in a situation where two set of words has similar meanings and the hyphen comes in to separate the words to gives it more meanings to it.
Hyphen helps serves as a modifiers which helps create a description with the use of the mark.
In the picture above, the first option has both "well and placed" as the modifiers and because they have same meaning which if use separately might makes the sentence wrong; so we make use of a modifier and it looks like well-placed there by making the sentence better