Which statement describes a condition indicating an unknown sample is not forbidden for air transport?

• A. The substance is not listed in any dangerous goods regulations
• B. The substance is explicitly forbidden for transport
• C. The substance is always allowed regardless of packaging
• D. The substance is not considered to be forbidden for transport under applicable air transport regulations

Answer: (D)

In air transport, the crucial question is whether the regulation says a substance is forbidden. The statement that the unknown sample is not considered forbidden for transport under applicable air transport regulations is the best choice because it directly reflects this regulatory test: if something isn’t forbidden under the current rules, it may be transported, provided packaging, labeling, and documentation meet the requirements. It doesn’t rely on being listed or not, and it doesn’t claim it will always be allowed regardless of packaging.

Why the other ideas aren’t as appropriate: being not listed in regulations does not guarantee it isn’t forbidden—there can be special provisions, exemptions, or future changes that apply. If something were explicitly forbidden, it cannot be transported. And saying it’s always allowed regardless of packaging ignores the real-world rules that require proper packaging and handling for any non-forbidden item.