On a recreational vessel more than 65 feet, gross tonnage is between 500 and 1,000. The minimum number of 20-B portable fire extinguishers required by tonnage is ______.

Why D is correct

Table 4 to 33 CFR §175.320(b)(1) specifies that a vessel over 500 GT but not more than 1,000 GT must carry a minimum of five 20-B portable fire extinguishers. Two applies to the 50–100 GT range; three to 100–500 GT; six to vessels over 1,000 GT.