A group of engineers has just conducted an experimental trial on a shoe designed to help people suffering from a painful foot disorder. During the trial, the shoe proved effective for only 5% of the test subjects. What should the engineers do next?

According to the passage, which of these is true about gray water systems? a) gray water systems use plants that require less water. eliminate b) gray water systems require the use of less fossil fuels. c) gray water systems reduce the amount of fresh water used. d) gray water systems reduce the amount water used by shower heads.