How does Dart's event loop handle microtasks vs the event queue?

A Dart processes all tasks in a single FIFO queue with no priority distinction B Microtask queue (higher priority — Future.then callbacks) is fully drained before the event queue (I/O, timers) processes its next event C Dart uses a thread pool for microtasks and a single thread for the event queue D Microtasks are for UI frame callbacks; event queue items are for network requests