I looked up the question and got D- a vacuum
Answer: Gamma rays
Explanation: The given waves belong to the electromagnetic spectrum which consists of different electromagnetic radiations arranged in terms of increasing wavelengths or decreasing frequencies.
Thus 
E= energy
= frequency
c = speed of light
= wavelength
Thus frequency and wavelength are inversely related. The waves having high energies ave high frequencies and have shorter wavelengths.
Thus gamma rays having highest energy have highest frequency and shortest wavelength.
The force required to start an object sliding across a uniform horizontal surface is larger than the force required to keep the object sliding at a constant velocity once it starts.
The magnitudes of the required forces are different in these situations because the force of kinetic friction is less than the force of static friction. <em>(d)</em>
The skydiver jumping from a plane high up in the sky would most likely experience various energy transformation. For starters, it would undergo a very large gravitational potential energy because of its much higher elevation. After jumping, this energy would eventually transform to kinetic energy due to the force exerted by the gravity.
