Question

One way to decrease the weight of an object is to

Answer 1

If you increased the speed of rotation of the Earth you would get a perceived decrease in the weight of the object due to an increased centrifugal force. 
Increase it fast enough and the momentum of the object will eventually overcome the gravitational pull on it and it will fly off the planet.

Answer 2

From that list of choices, ' D ' is the only one that will do the job.