To bill customers for water usage, one city converts the number of gallons used into units. This relationship is represented by the equation g = 748u, where g is the total number of gallons of water used and u is the number of units. Determine which statements about the relationship are true. Check all that apply.

g is the dependent variable.
u is the dependent variable.
g is the independent variable.
u is the independent variable.
The variables cannot be labeled without a table of values.
The variables cannot be labeled since any value can be selected for either.