Which of the following are the imaginary lines?

A)
Only streamline
B)
Streamline and pathline
C)
Pathline and streakline
D)
Streamline and streakline

Correct Answer :   Streamline and pathline


Explanation : Both Streamlines and pathline are imaginary because streamline represents the direction of the fluid flow from a particular point in the fluid flow domain. This point can be anywhere in the fluid domain and is imaginary. Pathline is the path traced by a fluid element at a given interval of the time.