Correct option is C
HGL represents piezometric head. i.e. it includes datum head and pressure but excludes velocity head.
When velocity head is added to HGL. it becomes TEL.
Importance:
The HGL is useful for understanding how the pressure changes within a flowing fluid and for designing piping systems to ensure that the pressure stays within desired limits.
In an open channel, the HGL coincides with the water surface, since the pressure head is zero.
