From the given,
All of Suman, vicky, santosh, mohan, alok, sagar, shekhar are standing on a wall facing west.
Mohan is at the extreme end, assuming as 1.
Santhosh is his neighbour, assuming as 2.
Alok is the third one from the end of south.
Since Sagar is standing between Santhosh and Shekhar, Santhosh has him on left side as a neighbour.
Final answer:
Hence, option C is correct.
Shekhar is standing to the left of Santhosh.