The correct option is B Japan
The 13th edition of joint military drill exercise Iron Fist 2018 was held between American and Japanese forces at Camp Pendleton in California on January 12 and continued till February 12. More than 500 U.S. Marines and sailors partnered with 350 members of the Japanese Ground Self-Defense Force to train in fire support operations and amphibious assaults. Iron Fist is an annual, bilateral training exercise where U.S. and Japanese service members train together and share techniques, tactics, and procedures to improve their combined operational capabilities.