The sample size is determined using the sampling procedure.

A sampling procedure in SAP S/4HANA QM (transaction QDV1) defines how samples are calculated and valuated for an inspection lot. Mandatory assignments ensure the system can determine and process the sample:

Sampling Type (C): This is a required field in the sampling procedure header. It specifies how the sample size is determined (e.g., fixed sample, percentage, sampling scheme). Without it, the system cannot calculate the sample size (e.g., "100% inspection" or "Attribute sampling").

Valuation Mode (D): Also mandatory, this defines how inspection results are evaluated (e.g., "Manual valuation," "Attribute inspection nonconforming units"). It’s assigned in the sampling procedure and ensures consistent acceptance/rejection rules.

Inspection Severity (A): This is optional and applies only to sampling schemes (e.g., normal, tightened), not all sampling types.

Unit of Measure (B): The unit of measure is inherited from the material or characteristic, not a mandatory assignment in the sampling procedure itself.

Thus, "Sampling type" and "Valuation mode" are the correct answers, as they are essential components of every sampling procedure.References: SAP Help Portal - "Sampling Procedures in QM"; SAP S/4HANA QM Customizing Guide - "Sample Management".