The tendency of a liquid surface to contract is due to the following property_________________?

A. Leag weir
B. Overflow weir
C. Siphon spill way
D. None of these

A. The presence of oxygen
B. The absence of oxygen
C. Both cases A. and B.
D. Neither A. nor B.

A. Both A and R is true and R is the correct explanation of A
B. Both A and R is true but R is not a correct explanation of A
C. A is true but R is false
D. A is false but R is true