Which of the following fresh water generators has an operating principle that evaporates pre-heated sea water by causing it to undergo a pressure drop into a vacuum?

Correct Answer: Option B — Flash type unit

Flash evaporators operate by heating pressurized seawater and then spraying it into a lower-pressure vacuum chamber. The sudden pressure drop causes the water to 'flash' into vapor instantly. This design is highly effective for marine applications as it minimizes the time water spends on hot surfaces.