To determine which line has a positive gradient, we need to analyze the direction of each line in the image.

A line has a positive gradient if it slopes upwards from left to right.

Analyzing the lines:

• Line A (green) is horizontal, meaning its gradient is zero (not positive or negative).
• Line B (purple) slopes upwards from left to right, meaning it has a positive gradient.
• Line C (blue) slopes downwards from left to right, meaning it has a negative gradient.
• Line D (red) is vertical, meaning its gradient is undefined.

Thus, Line B has a positive gradient.

The correct answer is B. Line B.

Would you like more details, or do you have any other questions?

Here are 5 related questions for practice:

1. What does a line with a negative gradient look like?
2. How do you calculate the gradient of a line given two points?
3. Can a horizontal line have a positive or negative gradient?
4. What is the gradient of a vertical line, and why is it undefined?
5. How would you sketch a line with a specific positive gradient?

Tip: Remember, the gradient of a line is the change in $y$ over the change in $x$, often referred to as "rise over run."