The correct answers are B. Cross-object field updates between Training and Student records are not supported and C. On Training record, the Student Lookup field can be made optional.

This question is about creating a Student lookup field on the Training object. A lookup relationship is a looser relationship than master-detail. Salesforce documentation explains that lookup relationships do not support roll-up summary fields, unlike master-detail relationships.

Because this is a lookup relationship, the Student lookup field on Training can be optional unless the app builder marks it required. Cross-object field updates are also not supported in this lookup relationship scenario; Salesforce documents that cross-object field updates work for master-detail relationship scenarios, not normal lookup relationships.

A is incorrect because roll-up summary fields require a master-detail relationship.

D is incorrect because deleting Student records is controlled by object permissions and relationship delete behavior, not simply by access from the Training record.

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