in the first item of the numeroted list, it is mentionned :

Include the questionnaire-itemExtractionContext extension either on the Questionnaire root or on 'group' items within the Questionnaire to identify the resource that will serve as the context for any extraction.

But it seems that the mentionned extension can be included in non group item :
https://chat.fhir.org/#narrow/stream/179255-questionnaire/topic/data.20extraction.20.3A.20itemextractioncontext

I think it would be interesting to rephrase the sentence quoted by something like :

Include the questionnaire-itemExtractionContext extension either on the Questionnaire root or on any item within the Questionnaire to identify the resource that will serve as the context for any extraction.