What is the meaning of the point with an x-coordinate of 3. A. The commuter train travels 3 feet in 180 seconds.

B. In 1 second, the commuter train travels 3 feet.

C. In 3 seconds, the commuter train travels 180 feet.

D. It takes the commuter train 60 seconds to go 3 feet

PLS HELP ASAP!!!

Apinhole camera is made out of a light-tight box with a piece of film attached to one side and pinhole on the opposite side. the optimum diameter d(in millimeters) of the pinhole can be modeled by d=1.9[ (5.5 x 10^-4) l) ] ^1/2, where l is the length of the camera box (in millimeters). what is the optimum diameter for a pinhole camera if the camera box has a length of 10 centimeters