Among the following choose the algae that are not used as food.
A. Porpyra
B. Spirogyra
C. Ulothrix
D. Volvox
A, B and C only
B, C and D only
A, C and D only
A, B, C and D
Porpyra is used as food. Volvox, Ulothrix and Spirogyra are not used as food but can be used as fish feed.