The correct answer is B) annually by the owner, with a letter submitted to the Coast Guard within one month of the anniversary date of the plan approval. This is correct because under 33 CFR 155.1060(c), the Shipboard Oil Pollution Emergency Plan must be reviewed annually by the vessel owner or operator, and a letter confirming the annual review must be submitted to the Coast Guard within one month of the anniversary date of the plan's original approval. The other options are incorrect because they do not accurately reflect the regulatory requirement for annual review and submission of the letter to the Coast Guard. Option A is incorrect as it only requires review every 5 years, Option C is incorrect as it requires the letter to be submitted 6 months before expiration, and Option D is incorrect as it requires the entire plan to be resubmitted every 5 years, which is not the case.