Answer:
C. Precipitate the crystals as fast as possible
Step-by-step explanation:
C. Precipitate the crystals as fast as possible
Precipitation if done fast , can lead to the formation of impure crystals , as impurities also get stuck inside the crystals. So it must be done slowly to obtain the pure crystals . Slower the crystals form , purer they are .
All the other options can lead to a successful recrystallization.