What is the grammatical term for the Egyptian Arabic future particle 'ḥa-' (حـ) prefixed to verbs, as in 'ḥa-yiktib' ('he will write')?

• A Prefix conjugation borrowed from Coptic grammar
• B Pre-verbal future marker derived from 'rāyiḥ' (going) ✓
• C Contracted form of the Classical future particle 'sawfa'
• D Subjunctive prefix inherited from ancient Egyptian verbal morphology

The Egyptian Arabic future marker 'ḥa-' is a grammaticalized contraction of the active participle 'rāyiḥ' ('going'), parallel to the 'going to' future in English — a feature unique to Egyptian among Arabic dialects.