challenge: What is the geographical area of responsibility of the 5th Regional Command of the Vietnam People's Navy?
  
  A. The waters of the South China Sea and the Gulf of Thailand, specifically off the provinces of Cà Mau and Kiên Giang
  B. The waters of the Pacific Ocean and the Sea of Japan
  C. The waters of the North China Sea and the Gulf of Tonkin
  D. The waters of the Indian Ocean and the Java Sea
  Answer: 