Definition: In this task, you're given a question, a context passage, and four options which are terms from the passage. After reading a passage, you will get a brief understanding of the terms. Your job is to determine by searching and reading further information of which term you can answer the question. Indicate your choice as 'a', 'b', 'c', or 'd'. If you think more than one option is plausible, choose the more probable option to help you answer the question.
Input: Question: How long did the construction of the USS Castle Rock take? Passage:USS Castle Rock (AVP-35) was a United States Navy Barnegat-class small seaplane tender in commission from 1944 to 1946 which saw service in the late months of World War II. After the war, she was in commission in the United States Coast Guard as the Coast Guard cutter USCGC Castle Rock (WAVP-383), later WHEC-383, from 1948 to 1971, seeing service in the Vietnam War during her Coast Guard career. Transferred to South Vietnam in 1971, she served in the Republic of Vietnam Navy as the frigate RVNS Tran Binh Trong (HQ-05) and fought in the Battle of the Paracel Islands in 1974. When South Vietnam collapsed at the end of the Vietnam War in 1975, Tran Binh Trong fled to the Philippines, where she served in the Philippine Navy from 1979 to 1985 as the frigate RPS (later BRP) Francisco Dagohoy (PF-10).
Links: a. Barnegat-class seaplane tender b. Frigate c. United States Navy d. South Vietnam
Output:
c