What cash crop, once the foundation of Egypt's 19th-century export economy, still bears the name 'white gold' locally?

• A Sugarcane
• B Flax
• C Long-staple cotton ✓
• D Rice

Egyptian long-staple cotton (Gossypium barbadense), introduced by Muhammad Ali in the 1820s, earned the moniker 'white gold' for its exceptional fibre length and lustre, which commanded premium prices on European textile markets and funded the country's early industrialization.