Answer:
Line 1 = Negative
Line 2 = Zero
Line 3 = Positive
Line 4 = Undefined
Explanation:
Line 1's gradient is negative since it's sloping down.
Line 2's gradient stays at 0 since it does not go upwards or downwards.
Line 3's gradient is positive since it's tilting upwards.
Line 4's gradient is undefined since the line shoots up on the same point on the x-axis so the gradient cannot be determined by a single rational number.