International Oil Pollution Prevention (IOPP) Certificates are required for each U.S. oil tanker at or above how many gross registered tons?

Correct Answer: Option D — 150 gross registered tons

MARPOL Annex I and 33 CFR 151.17 require an International Oil Pollution Prevention (IOPP) Certificate for all oil tankers of 150 gross tons and above, and for other ships of 400 gross tons and above, to verify compliance with international pollution prevention standards.