Question 4
How is a solid solute made to crystallise out of a solution?
The right answer is the one marked above.
It is concentrated. Evaporating a saturated solution pushes the solute concentration past the maximum that can stay dissolved, so the solute leaves as crystals.
Diluting does the opposite. Cooling is part of recrystallisation, which is a different operation aimed at purity rather than at getting the solid out at all.