The process that causes minerals to become concentrated in certain areas is primarily tectonic movement . This process involves the shifting of the Earth's tectonic plates, which can lead to the formation of rich mineral deposits. Other options like volcanic activity and siltation do not primarily focus on mineral concentration. ;
The best answer to the question is C. Tectonic movement, which refers to the movement of the Earth's tectonic plates that leads to the concentration of minerals. This process creates the necessary conditions for mineral deposits to form through geological activities and changes. Other options like volcanic activity and siltation do not primarily focus on the systematic concentration of minerals as tectonic movement does.
;