The speed of sound is greater in ice (4000 m/s), then in water (1500 m/s), then in air (340 m/s). The explanation for this is the differente state of the matter in the three cases.
In fact, sound waves travel faster in solids (like ice), then in liquids (like water), then in gases (like air). This is because the speed of the sound wave depends on the density of the medium: the greater the density, the faster the sound wave. This can be easily understood by thinking at how a sound wave propagates: a sound wave is a vibration of molecules, which is transmitted throughout the medium by collision of the molecules. Therefore, the smaller the spacing between the molecules (such as in solids), the more efficient is the propagation, and so the sound wave is faster. On the contrary, there is a large spacing between molecules in gases (such as in the air), so there are less collisions between the molecules and so the wave is not transmitted efficiently, and so it has less velocity.
The image is missing (however it's not necessary to solve the problem).
The correct answer is A) decreases, because the gravitational force is inversely proportional to the square of the distance. In fact, the magnitude of the gravitational force between two object of mass M and m, at a distance d one from each other, is
where G is the gravitational constant. As can be seen from the formula, if the distance d between the two object increases, the intensity of the force decreases.