Sentence Correction (SC) | Re: Most of Portugal's 250,000 university students boycotted classes in a

Hello AndrewN ,

I have seen in official correct answers for the usage of instead in which shall be followed by noun as it is a preposition.
However , for the case in correct answer , ‘ instead of ‘ is followed by participle adverb .
Is this usage acceptable ?
I eliminated this choice on the basis of above .

Thanks.