To ensure only specific branch staff can create opportunities for high-risk products, set the Price Book OWD to View Only to limit access. Then, use a sharing rule to share the high-risk price book with the trained staff. This approach ensures:

Untrained users cannot see or use the price book.

Trained staff have explicit access through the sharing rule.

Option A: Manual sharing is inefficient for a large group and less manageable than sharing rules.

Option C: While technically correct, sharing rule implementation is clearer and more scalable for this use case.