The implementation choice has to match the object context. Use B. The Allow reparenting checkbox, Child records can be reparented to other parent records after they are created, is uncheckedd. The selected option is not chosen because it sounds familiar; it is chosen because it gives Salesforce the right instruction at runtime.
Lookup relationships connect records while allowing looser ownership and lifecycle control than master- detail. They are appropriate when records should remain more independent or when the relationship is optional.
The scenario describes a business outcome, not merely an administrative preference. If the feature is configured correctly, users get the intended result without depending on memory, spreadsheets, or manual policing. That is the professional standard for Platform App Builder work: place the rule in metadata, test it under the correct permissions, and keep the design supportable.
The other choices would leave a gap in the implementation. A (The Read Only radio button, Allows users with at least Read access to the Master record to create, edit, or delete related Detail records, is selecte) misses the mark because Master-detail is powerful, but it is wrong when the records need independent ownership or when the child-parent direction is reversed. C (The Read/Write radio button, Allows users with at least Read
/Write access to the Master record to create, edit, or delete related Detail records, is selecte) handles a different concern; Master-detail is powerful, but it is wrong when the records need independent ownership or when the child-parent direction is reversed. D (The Allow reparenting checkbox, Child records can be reparented to other parent records after they are created, is checked) is less defensible because That field type either stores the wrong kind of value or fails to support the required behavior as cleanly as the selected option.
In a real org, the builder should include negative testing as well, proving that the rule does not fire or display outside the intended conditions.
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