واحد فقط من هؤلاء الشعراء لم يكن في عهد عبد الملك بن مروان

The error in the answer is that the poet Hassaan ibn Thabit did not live during the time of Abd al-Malik ibn Marwan. This is an inferential answer as there were no names of poets provided to choose from. The request is for future questions to be clearer and more specific to ensure a clear and correct answer is given.