What is the Arabic name for the informal, unlicensed microbus system that forms the skeleton of Cairo's chaotic public transport network — vans that stop anywhere on hand signal and carry 14 passengers in a vehicle built for 10?

• A Mashru'
• B Kibbutz
• C Sarfis ✓
• D Toktok express

The sarfis (from 'service') is a shared-ride van that operates on a fixed route but with no fixed stops — passengers signal to board, pay coins passed hand-to-hand to the driver's assistant, and shout 'ala yamin' ('on the right') to alight, forming a spontaneous, self-organizing transit system that fills the gaps left by formal bus routes.