What is difference between unfold and untie

[ivy]

Test No. incompl/inter-29 "Who has done it?", question 5

As the plot ........., you find yourself agreeing with one character's solution and then another's.

(a) undoes
(b) unfolds
(c) unties
(d) unfurls

Test No. incompl/inter-29 "Who has done it?", answer 5

As the plot unfolds, you find yourself agreeing with one character's solution and then another's.

Correct answer: (b) unfolds

Your answer was: incorrect
As the plot unties, you find yourself agreeing with one character's solution and then another's.
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what is difference between unfold and untie?

[Mister Micawber]

.
I am sure that you can find the difference in your dictionary between fold (which is the manipulation of a planar object) and tie (which is the manipulation of a linear object)-- but the point here is that unfolding is what plots, stories and narratives do: unfold means reveal gradually by written or spoken explanation; make known.
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Native English teacher at Mister Micawber's