The correct answer is: A. T-806.
T-806 is a token block system that is used to control train movements in double-track sections. It is a centralized traffic control system that uses a token to authorize trains to enter a section of track. The token is held by the train that is occupying the section of track, and it is passed to the next train that is authorized to enter the section. This system ensures that there are no collisions between trains.
To perform shunting beyond LSS at station of double line equipped with T-806, the authority of the station master is required. The station master will issue a shunting permit to the shunting locomotive driver. The shunting permit will authorize the shunting locomotive driver to enter the section of track that is beyond the LSS.
The other options are incorrect because they are not token block systems. T/A 802 is a train order system, T/A 602 is a manual block system, and T-806 A is a type of automatic block system.