Which of the following describe the earth's magnetic declination? the angle between earth's magnetic field and earth's surface earth's magnetic field strength at the equator the tendency for the earth's field to reverse itself the angle between true north and north indicated by a compass

There's no such thing as "the Earth's magnetic declination", because
magnetic declination is different for each place on Earth.

It's the difference between true north and the direction a compass points.

You could say that the magnetic declination at a certain place is
the measurement of how 'wrong' a compass is at that place.
 

10 percent is approximately lost at each energy level in the energy pyramid.