Computer Networks, OSI model What layer of OSI model does define the route of information transmission between sender and receiver computers?


A) Session layer
B) Physical layer
C) Data link layer
D) Network layer
E) Transport layer

In this question I think answer must be Network layer.But my teacher insists that answer is Transport layer.Even though i have shown in so many books it was written like that:

"Path Determination. The network layer must determine the route or path taken by packets as they flow from a
sender to a receiver. The algorithms that calculate these paths are referred to as routing algorithms."

this is from book that name is "Computer Networking: Top-Down approach, 5th edition,James Kurose", 

chapter 4.1.Introduction and Network Service Models
The Transport layer offers services as:


Connection-oriented communication
Same order delivery
Reliability
Flow control
Congestion avoidance
Multiplexing


The network layer is responsible for packet forwarding including routing through intermediate routers.

The answer is definitely Network layer.