Concept:The Treaty of Nanjing was a peace agreement that ended the First Opium War and forced China to give territory to Britain.Explanation:The Treaty of Nanjing was signed in 1842.It brought the First Opium War, fought between the United Kingdom and China, to an end.Under its terms, China was required to cede the island of Hong Kong to the British Empire.This cession gave Britain a permanent strategic base for trade in the region.Answer:Hong Kong (Option B).