Which table shows a function that is decreasing only over the interval (–1, ∞)?

The table to the farthest right.

Explanation:

The interval (-1, ∞) represents x-values anywhere from -1 and higher.  

As such, you are looking for a table with y-values that decrease as the x-values increase.

Starting from -1 -

The first option: -5, -2, -1, 2. This is increasing.

The second option: -7, -6, 1, -1. This increases from -7 to -6 to 1.

The third option: -1, 2, 1, -6. This increases from -1 to 2.

The fourth option: 1, 0, -4, -8. This decreases across all coordinates in the range specified.