Is there a relationship between the direction of movement and distribution of earthquakes? volcanoes? both? neither?

Yes. With converging plates, where two plates are touching towards each other instigating one to sub duct beneath the other, you incline to have volcanoes and earthquakes. Instance: In Asia, the Pacific Plate touching to and beneath the Eurasian Plate. Another example of where you would have earthquakes is where two plates are slipping in contrary directions parallel to one another. This is an instance of the Pacific Plate touching next to the North American Plate. This makes faults or crashes in the plates instigating earthquakes. As the plate slip past each other, subsequently separately plate boundary isn't flawlessly smooth, they catch on one another and accumulate pressure. When the pressure is free, the energy is gave out as an earthquake.

one person pulls 90n one way and the other has 100n pulling the other way.

so the net force = 90 - 100 = -10n,

or the ans can be 10n if the picture shows -90n and 100n instead.

the answer is the first electromagnet (a). this is because it has more coils around the ferromagnetic material. increasing the number of coils increases the surface area in which the metal interacts with the current in the coil. this enables more atoms in the metal to become aligned hence becoming more magnetized.