أنشئ حسابًا أو سجّل الدخول للانضمام إلى مجتمعك المهني.
A. roads
B. retaining walls
C. lining of canals
D. lining of tunnels
E. all the above.
The right answer is under: E. all the above.
A very 'Smart' Question!
I would choose option:
E: all the above