#### Answer

(a) is increasing on the interval $(-\infty, -1)$
(b) is decreasing on the interval $(-1, +\infty)$
(c) has no interval where it is constant

#### Work Step by Step

Based on its graph, the given function:
(a) is increasing on the interval $(-\infty, -1)$
(b) is decreasing on the interval $(-1, +\infty)$
(c) has no interval where it is constant