Consider the following statements:
Assertion (A) The velocity of sound in air increases due to the presence of moisture in it.
Reason (R ): The presence of moisture in air lowers the density of air.
Of these statements-
A. both `A` and `R` are true and `R` is the correct explanation of `A`
B. both `A` and `R` are true but `R` is not the correct explanation of `A`
C. `A` is true but `R` is false
D. `A` is false but `R` is true
