Answer:
The correct option is Z
Step-by-step explanation:
Active transport can be described as the movement of molecules against a cell's concentration gradient; meaning the movement of molecules across the cell's membrane from a region of lower concentration to a region of higher concentration. From this, it can be deduced that to have active transport in the description in the question, the "body" (the cell or the liquid) with the most amount of magnesium took in more magnesium (showing movement against concentration gradient as the magnesium moved from the least side to the most side). Thus, the correct option is Z