The reaction $$X + Y \rightarrow Z$$ is first order with respect to X and second order with respect to Y. The initial rate of formation of Z is R $$\text{mol dm}^{-3} \text{s}^{-1}$$ for given initial concentrations of X and Y. If $$[X]_0$$ is halved and $$[Y]_0$$ is doubled, the value of the initial rate would become

A

4R

B

$$\frac{R}{4}$$

C

R

D

2R