The figure below shows a line graph and two shaded triangles that are similar:

Which statement about the slope of the line is true?

It is fraction negative 1 over 3 throughout the line.
It is −3 throughout the line.
The slope from point O to point A is fraction 1 over 3 times the slope of the line from point A to point B.
The slope from point O to point A is three times the slope of the line from point A to point B.