What is the name of the desert-adapted plant — a woody shrub found in the Western Desert depressions — whose fruits were a staple food of the Siwa Oasis and whose leaves were used as a traditional soap and shampoo?

• A Ghurd (Hammada elegans)
• B Retem (Retama raetam)
• C Araq (Salvadora persica)
• D Sidr (Ziziphus spina-christi) ✓

Araq (Salvadora persica, also called the toothbrush tree or miswak tree) produces small, peppery red berries eaten fresh or dried by Bedouin communities, while its fibrous roots and twigs — when chewed — release antibacterial compounds and form the traditional miswak tooth-cleaning stick recommended in Islamic hygiene practice.