Are private firearm sales allowed in Hawaii without a background check?

In Hawaii, all firearm sales, including private sales, require a background check. This measure is in place to help ensure that individuals who purchase firearms are eligible to possess them under the law. Background checks are a crucial part of the gun purchasing process to promote public safety and prevent individuals who are prohibited by law from owning firearms from obtaining them easily. Therefore, option C is the correct answer.

Options A, B, and D are incorrect because they suggest that there are exceptions to the background check requirement for private firearm sales in Hawaii, which is not the case.