Select the most appropriate option that can substitute the highlighted segment in the given sentence.
All the guests I have invited to the movie screening have shown unwilling due to their busy schedules.

Correct option is A

The correct substitution for the highlighted segment is (a) "have shown unwillingness."
"Have shown unwillingness" correctly reflects the guests' general disposition towards attending the event, expressed in a grammatically correct form.
Grammatical rule used: "Unwillingness" is the noun form that fits the structure of the sentence, indicating the state of being unwilling.
Example: Despite the incentives, there was significant unwillingness among employees to relocate.