Question

One group of students uses different methods to conserve water as listed below.

Answer 1

The best answer is b) Method 1 and Method 3

Method 2, which is part of every other options, does involve using extra water because the dishwasher will necessarily use extra water, even if it is full when you use it. 
On the other hand, fixing leaky faucets requires no extra water and the recycled water used to wash your car has already been used.