I think the answer should be a I’m not sure tho
Because noble gases has full of 8 electron in her external cell......
1. Centimeter
2. Kilogram
3. Millisecond
4. DL
5. Kg
6. Mm
7. S
8. Mm
9. Us
Here we can say that rate of flow must be constant
so here we will have

now we know that


now from above equation



so velocity will reduce by factor 0.14
Hello!
The best explanation is the new "experimental evidence", which occur with the help of new and improved technology. For this question, I suggest you to answer letter b).
Hugs!