This is a correcing-gramatial-error question from the IELTS OG. the relavant picture is provided here
Acccording to the answer, error No.10 "is extending" is replaced with "has been extended", which sounds incorrect to me.
In my view, the subject being described by "which" is " the supermarket and the hotel", so the correct answer should be "have been extended".
I would like a second opinion on this.