Entropy change of the reaction, H2O(liquid) ⇒ H2O(gas), is termed as the enthalpy of

Answer: Option B

$$A.$$ solid ⟹ liquid → melting
$$B.$$ liquid ⟹ vapor → vaporization
$$C.$$ solid ⟹ vapor → sublimation
So, enthalpy change for the reaction $$H_{2}O\left(liq\right)\Rightarrow H_{2}O\left(gas\right)$$     is enthalpy change of vaporization.
In the question entropy should be replaced by enthalpy.