Hadith comprehension

Which expression is an iḍāfah construction in “مَطْلُ الْغَنِيِّ ظُلْمٌ”?

Travel, repayment, service, and sufficiency (Hadith 37–43)

• ظُلْمٌ
• الْغَنِيِّ ظُلْمٌ
• مَطْلُ الْغَنِيِّ
• مَطْلُ ظُلْمٌ