When data is transmitted from device A to device B, the header from A layer 5 is read by B's _____ layer.

The correct answer is: option 3: Session

Key Points

In the OSI (Open Systems Interconnection) model, data is transmitted from the topmost layer (Layer 7 – Application) to the lowest (Layer 1 – Physical) on the sender’s side and then travels back up from Layer 1 to Layer 7 on the receiver’s side.

Layer 5 is the Session Layer.

So, when data is transmitted from device A to device B, the header added by Layer 5 on device A (Session Layer) is read and processed by Layer 5 on device B.

Explanation of options:

• Option 1 – Presentation: ❌ Layer 6, handles data format and encryption/decryption.
• Option 2 – Transport: ❌ Layer 4, responsible for reliable transmission (TCP/UDP).
• Option 3 – Session: ✅ Correct. It's Layer 5, which manages sessions and its header is read by the peer Session Layer.
• Option 4 – Physical: ❌ Layer 1, deals with transmission of raw bits.

Hence, the correct answer is: option 3: Session