Final answer:
In the given equation, g is the independent variable and u is the dependent variable.
Step-by-step explanation:
The given equation is u = 74g, where u represents the number of units and g represents the total number of gallons of water used.
To determine the relationship between the variables, we need to understand the concepts of independent and dependent variables.
In this equation, g is the independent variable because it is the input or the value that can change. u, on the other hand, is the dependent variable because it depends on the value of g. For every value of g, there is a corresponding value of u.
Therefore, the correct statements about the relationship are:
a) g is the independent variable.
b) u is the dependent variable.