Which of the Following Statements Is LEAST-Likely True

Which of the following statements is LEAST-Likely true?

A) Ethylene glycol coolant is mixed with purified water until its concentration is correct.
B) When coolant strength has been allowed to become weak through dilution or additives are depleted, a coolant flush and change is recommended.
C) Draining off a quart of coolant and adding straight coolant can weaken a slightly weak concentration.
D) Coolant in too high a concentration can be further diluted with purified water.