Which commodity would be regulated by subchapter D, Rules and Regulations for Tank Vessels?

Correct Answer: Option C — Asphalt

Title 46 CFR Subchapter D regulates tank vessels carrying combustible and flammable liquid cargoes. Asphalt, having a flashpoint and transport characteristics fitting these criteria, falls squarely under Subchapter D regulations, unlike hazardous chemicals governed by Subchapter O.