Answer
(d) none of the preceding
Work Step by Step
The speed of the object measured by the observer moving relative to the object is not same as the actual speed of the object. This is because the observer is at rest in his frame, so the speed of the object measured by him is either the sum of actual speed of the object and his speed or the difference of the two speed.
Since speed is the magnitude of the velocity, the velocity measured by hum is also not correct.
Kinetic energy depends on the source of velocity. Kinetic energy of the object measured by the observer is also not same as actual kinetic energy of the object.
