Here it is.

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Don't think so, where is the sp3 C in vinylgroup?

vinylic carbon are less reactive for  nucleophilic substitution reactions because halogen is bonded to sp² carbon.
Sp² carbon halogen bonds are shorter and stronger than sp³ carbon halogen bond because of small size of sp2 orbitals.
Due to this stronger bonds vinylic halogens do not undergo nucleophilic substitution reactions.

So is it a mistyping in the solution b or is c the right answer now.?

There is no mistyping in the question. It was marked wrong by the student and thats why the question is here on the forum as a doubt.

With other words no answer fullfill the correct answer.

Quote from: chenbeier on August 29, 2021, 11:46:34 AM
With other words no answer fullfill the correct answer.

No C is correct answer with correct words.