What layer of OSI model does TLS operate?
Transport Layer
This is not correct, it's the session layer of the OSI model
SSL was created with the TCP/IP model in mind, not the OSI
model. While it is technically true SSL or TLS is in the Session
Layer of the OSI, it should be referred to in conjunction with the
TCP/IP Model. In this case, it resides above the Transport Layer,
providing security for it, hence the name of SSL's successor
Transport Layer Security (TLS).
Note: TLS 1.0 is SSL 3.1
FYI, please take note the ITU X.800 recommendation states there
are no security services provided in the session layer.