40/396 simplified can you help

What is the equation of the linear function represented by the table?

Which term best describes the association between variables a and b? no association a negative linear association a positive linear association a nonlinear association a scatterplot with an x axis labeled, variable a from zero to ten in increments of two and the y axis labeled, variable b from zero to one hundred forty in increments of twenty with fifteen points in a positive trend.

[10 points, algebra 2]according to my answer key the restrictions are -1 and 4. but why not positive 1?