You want to block purchasing of a material from a supplier due to quality reasons.

Blocking purchasing from a supplier for quality reasons is managed in:

Quality Info Record: Procurement (C): In the quality info record (transaction QI01), you can set the "Block" indicator or use a status profile (e.g., "Blocked") to prevent purchasing from a supplier for a specific material. This is the standard QM object for supplier-material quality control (SPRO > QM > Quality Inspection > Quality Info Record > Define Status).

Material (A): The material master can block overall procurement but not supplier-specific QM issues.

Business Partner (B): Blocking a supplier globally is possible (e.g., via MM06), but notmaterial-specific for quality reasons in QM.

Purchase Order Item (D): POs can’t enforce a quality block; they reflect existing restrictions.

Thus, "Quality info record: Procurement" is the correct answer.References: SAP Help Portal - "Blocking Suppliers in QM"; SAP S/4HANA QM User Guide - "Quality Info Record".