Answer:
D. negative
Explanation:
Let's analyze each answer choice.
A. Zero
A line with a zero slope is a horizontal line. The x values change, but the y values stay the same.
B. Undefined
A line with an undefined slope is a vertical line. The x values don't change and the y values vary.
C. Positive
When a line has a positive slope, the line increases from left to right.
D. Negative
When a line has a negative slope, the line decreases from left to right.
When we move from left to right on the graph, the line moves down. Therefore, this line must have a negative slope and D is correct.