D Deepak Sahoo 🎓 Tutor II ⭐ 10.83K Points 📊 Computer Q. X.21 protocol consists of (A) Physical and frame levels (B) Frame and packet levels (C) Physical, frame and packet levels (D) Only physical level 👁️ Show Answer 🔗 Share ⚡Menu ✅ Correct Answer: (D) Only physical level You must be Logged in to update hint/solution 💬 Discussion 💬 Comment