In this task, you're given a question, along with a context passage which has extra information available on certain terms mentioned in it. Your job is to determine which sentence(s) from the passage can be used to search for further information needed to answer the question.
Q: Question: Which of the two trading partners of the port of Karachi in the eighteenth century has the largest population now? Passage:The Manora Island and was visited by Ottoman admiral Seydi Ali Reis and mentioned in his book Mir'at ul Memalik in 1554. According to the British historian Eliot, parts of city of Karachi and the island of Manora at port of Karachi constituted the city of Debal. The island was the site of a small fort constructed in the eighteenth century when the port of Karachi traded with Oman and Bahrain. The Kalmati Baloch tribe was settled in Karachi and they raised an army to defend the port from the British invasion. The Kalmati forces were defeated when the Manora Fort was stormed by the British in 1839 because of the strategic location of Karachi. Although the fort is now buried beneath the naval base, the lighthouse is a visible reminder of the British presence having been built in 1889 by the Canadian engineer Alain-Chartier-de-Lotbiniere Joly de Lotbiniere to assist vessels approaching Karachi harbor.

A:
The island was the site of a small fort constructed in the eighteenth century when the port of Karachi traded with Oman and Bahrain