By law, a user of marijuana shall be subject to which of the following?

Correct Answer: Option B — revocation of Merchant Mariner Credential

Under 46 CFR 16.201 and related DOT regulations, the use of dangerous drugs, including marijuana, is strictly prohibited for safety-sensitive positions. A positive drug test or confirmed use constitutes a violation of federal maritime safety standards, resulting in the mandatory suspension or revocation of the mariner's Merchant Mariner Credential.