For an exponential decay function in the form \( y = a(b)^x \), where \( 0 < b < 1 \):
- The function is always decreasing, not increasing, as \( x \) increases.
- The y-intercept is at \( (0, a) \).
- The domain includes all real numbers (\( (-\infty, \infty) \)).
- The range includes all real numbers greater than 0 (\( (0, \infty) \)), but not all real numbers because the output will never reach 0.
Thus, the correct statement about the graph of this function would be:
The domain includes all real numbers, the y-intercept is at \( (0, a) \), and the horizontal asymptote is at \( y = 0 \).
So the last response option is the correct one.