Earth has been cooling since its formation, if this is the case, why is it still hot inside? A Peridotite xenoliths
B Planetesimals crashing into each other
C Radioactive decay
D Seismic waves

None   they are   equally likely to occur on any plate boundary

Answerrecharge zone;

If a particular resource is not useful or needed then the price would be considerably low. once that resource is needed the price or value will raise depending on how useful or needed it is especially if the resource is low in quantity, the consumers would pay whatever they have to, to get that material.