The graph of f(x) = 6(0.25)x and its reflection across the y-axis, g(x), are shown. On a coordinate plane, 2 exponential functions are shown. Function f (x) decreases from quadrant 2 into quadrant 1 and approaches y = 0. It crosses the y -axis at (0, 6). Function g (x) approaches y = 0 in quadrant 2 and increases into quadrant 1. It crosses the y-axis at (0, 6).
What is the domain of g(x)?

all real numbers
all real numbers less than 0
all real numbers greater than 0
all real numbers greater than or equal to 0