Earthquake foci (focus, singular)
1) more than 200 miles
2) 0-50 miles deep
3) deep 50-200 miles deeo
4) all the above

3. depth of 50 - 200 miles.

Explanation:

The foci is the focus spot down below the epicenter where the earthquake occurs in the crust and upper mantle. The presence of a subduction zone where the plate collides with one another. The earthquake range from 0-800 mile of depth the deep foci earthquakes are of range 50 to 300 miles as the stress regimes are deeper downwards like a dip down. This zone is also called as the dipping seismic or the wadis Benioff zone. As the san Andreas fault has a shallow depth of about 20 m depth which is considered the deepest.

The answer to that would be magnesium