What is the Egyptian Arabic phonological phenomenon whereby the Classical emphatic consonant 'qaf' (ق) is systematically realized as a glottal stop (ء) in Cairo and the Delta?

• A Qaf velarization into kaf
• B Qaf pharyngealization into 'ayn
• C Qaf lenition to hamza ✓
• D Qaf labialization into waw

In Cairene and Delta Egyptian Arabic, the uvular stop ق (qaf) has undergone lenition into the glottal stop ء (hamza), so 'al-qalb' (the heart) is pronounced 'il-ʾalb' — a distinguishing feature that separates Lower Egyptian speech from Upper Egyptian (Saʿidi), where ق is preserved as a voiced velar [ɡ].