With whom did Britain sign treaties in 1802 to protect British commerce?

Britain signed treaties in 1802 with the Imam of Mocha and the Sultan of Aden primarily to secure and protect British commercial interests in the region, particularly in relation to trade routes and maritime navigation. The treaties aimed to establish peaceful trade relations, which were essential for promoting British economic activities, especially in the Arabian Sea and the Red Sea areas, where British merchants were increasingly active during that period.

The choice of the Imam of Mocha and the Sultan of Aden as treaty partners highlights the strategic importance of these local rulers, whose territories were key points for trade between Europe and the East. Securing alliances with them allowed Britain to ensure safer passage for their ships and goods, countering any potential threats from rival maritime powers and local factions that might disrupt commerce.

This context clarifies why this particular answer is the correct choice, as the treaties specifically addressed the need for protection of British commercial interests in the region, distinguishing it from the relevance of other figures mentioned in the other options at that time.