which is a valid velocity reading for an object?\no 45 m/s\no 45 m/s north\no 0 m/s south\no 0 m/s

Brief Explanations:

Velocity is a vector quantity, which means it has both magnitude and direction. A valid velocity reading should include both. While speed (a scalar) only has magnitude. Options with just magnitude like 45 m/s and 0 m/s are speeds. Options with magnitude and direction like 45 m/s north and 0 m/s south are valid velocity readings as they specify both how fast an object is moving and in what direction.

Answer:

B. 45 m/s north, C. 0 m/s south