ACT Math Practice Question

The initial speed, in miles per hour, of a certain car that skids to a stop can be estimated by multiplying the length of the skid, in feet, by 35 and then taking the square root of the product. According to this method, what is the estimated initial speed, in miles per hour, of the car when it makes a 108-foot skid?

1. A.$\sqrt{143}$
2. B.$7\sqrt{105}$
3. C.$6\sqrt{105}$
4. D.$210\sqrt{3}$