टी.सी.पी./आय.पी. मॉडेलमध्ये ______ ह्या नेटवर्क लेयरचा समावेश नसतो.

The correct answer is Option B (Internet layer).

Key Points:
• Comparison between the OSI Reference Model and the TCP/IP Protocol Suite:
• The OSI 7-layer model includes: Physical, Data Link, Network, Transport, Session, Presentation, and Application layers.
• The classical TCP/IP model has 4 layers:
• 1. Application Layer (incorporates functions of OSI Session, Presentation, and Application)
• 2. Transport Layer (Host-to-Host)
• 3. Internet Layer (corresponds to OSI Network layer)
• 4. Link / Network Interface Layer (corresponds to OSI Physical & Data Link)
• Therefore, Presentation Layer is present in OSI, but completely absent as an independent layer in TCP/IP.
• While the Presentation Layer is conceptually absent in TCP/IP, the official MPSC Final Answer Key for Set A assigned Option (2) ('Internet layer') as the correct answer.
• As per Priority 1 (Official Final Answer Key), Option (2) is designated.
• Key Takeaway: Per the official MPSC answer key, Option 2 is marked; technically, Presentation and Session layers are absent in the 4-layer TCP/IP suite.