A. a tsunami
(if the earthquake is hitting the ocean, the water will get effected)
Earth's magnetic field is the force acting on the compass needle to cause it to point northeast.
D
The motion of an object in a circle at a constant speed.
Mathematical equations can express dependencies between things, for example the relationship between the speed and acceleration. This can be summarized under "scientific laws".
More complex laws can represent models, for example a model of a human brain on a neuronal level could be based on complex mathematical equations.
D) all of the above is the answer