Which definition of the slope of a line is correct?

1. The slope of a line measures its strength.

2. The slope of a line measures how the input (y) changes in relation to how the output (x) changes.

3. The slope of a line measures its length.

4. The slope of a line measures how the output (y) changes in relation to how the input (x) changes.

Answer:Step-by-step explanation:It’s number 4 the last answer