Answer:
Green: Positive
Red: Zero
Black: Negative
Blue: Undefined
Step-by-step explanation:
Green: as x increases, y increases so there is a positive slope
Red: A horizontal line has a slope of zero because slope is rise divided by run, rise is zero, zero divided by anything is zero.
Black: as x increases, y decreases so there is a negative slope.
Blue: a vertical line has a run of zero and slope is rise divided by run but we cannot divide by zero so it is undefined.