Elongated hyphens would make this sentence grammatically correct: gideon and francis took a difficult but not interesting science course.

which sentence demonstrates the correct use of elongated hyphens? (4 points)

gideon - and - francis took a difficult but not interesting science course.
gideon and francis took a difficult but not - interesting science - course.
gideon and francis took a difficult - but not interesting - science course.
gideon and francis - took a difficult - but not interesting science course.