Final answer:
The main constraint faced by the Sultan of Brunei is the overreliance on oil and natural gas exports. To address this, Brunei is working towards diversifying its economy through the development of other industries and free trade zones.
Step-by-step explanation:
The main constraint faced by the Sultan of Brunei is the overreliance on oil and natural gas exports. Brunei's economy heavily depends on these resources, which make up 90 percent of its exports and over half of its GDP. This overreliance leaves the country vulnerable to fluctuations in global oil prices and the depletion of these finite resources in the long term.
To address this constraint, Brunei has been working towards diversifying its economy by expanding industries such as agriculture, tourism, and finance. Additionally, the government has been focusing on reducing unemployment and attracting international trade through the development of free trade zones.