In Van Vugt's (2001) Study of Water Consumption, What Was

In Van Vugt's (2001) study of water consumption, what was found?

A) People with a fixed tax rate use less water when they identify highly with their community than when they do not identify highly.
B) People with a variable tax rate use about the same amount of water regardless of their community identification.
C) People with a fixed tax rate use more water when they identify highly with their community than when they do not identify highly.
D) Both a and b.