Which solution is the most concentrated?

The correct answer is letter C. 6 moles of solute dissolved in 4 liters of solution with 1.5 M.

Here are the choices.

A. 1 mole of solute dissolved in 1 liter of solution (1 M)
B. 2 moles of solute dissolved in 3 liters of solution (0.67 M)
C. 6 moles of solute dissolved in 4 liters of solution (1.5 M)
D. 4 moles of solute dissolved in 8 liters of solution (0.5 M)

The activity series is shown in the attached picture. if the element is below the other, then you can displace the other. following the activity series as a guide, the reactions are as follows: nickel and aluminum chloride3 ni + 2 alcl₃  → 3 nicl₂ + 2 albarium and copper bromideba + cubr  →  no reaction because cu is less oxidizable than bapotassium nitrate and aluminum3 kno₃ + al  → al(no₃)₃ + 3 ksodium phosphate and zincnaso₄ + zn  → znso₄ + na

The answer is 4 i don't know if its right let me see.