This 'Questions' field is appearing in the Condition Builder because it is a back-end field that is used by the Variable Editor to ensure that variables are displayed correctly for any [task] related record.
Whilst the most common Use Case for the Variable Editor is for the Service Catalog Request process, it is also used by Record Producers. Such Record Producers have the ability to create a record either in the [task] Table or any table extending from [task]. Examples: [incident], [problem]. This means that these records can also be associated with Variables / Questions [item_option_new] that are passed from the Service Catalog.
Since Task Records do not have the same system architecture as displayed by the Service Catalog, instead the Questions (Variables) field is used to store the values that are entered during the submission of one of these Record Producers.
Some of this information is briefly touched upon in our Service Catalog Documentation.