Final answer:
Attribute sampling is the appropriate approach because it assesses compliance with binary attributes, such as the preparation of a required shipping document for hazardous materials.
Step-by-step explanation:
When management is legally required to ensure 100% compliance with the procedure of preparing a shipping document for the movement of hazardous materials, the most appropriate sampling approach is Attribute sampling. This type of sampling is used to determine if items in a sample comply with a designated attribute, in this case, the presence or absence of a shipping document. Since the question relates to whether or not a specific procedure has been followed (the procedure being binary, either complied with or not), attribute sampling is the correct choice over other types like variables sampling, discovery sampling, or targeted sampling.