Nickel forms a gaseous compound of the formula $$Ni(CO)_x$$. What is the value of $$x$$ if under similar conditions of temperature and pressure, methane effuses $$3.24$$ times faster than the compound. 

(For Ni, $$M = 58.7$$)

A

$$3.9$$

B

$$2.1$$

C

$$4.7$$

D

$$3.0$$