In a box, there are $5$ green balls and $10$ blue balls. A person picks $6$ balls randomly. The probability that the person has picked $4$ green balls and $2$ blue balls is

1. $\dfrac{42}{1001}\\$
2. $\dfrac{45}{1001}\\$
3. $\dfrac{240}{1001} \\$
4. $\dfrac{420}{1001}$