#### Answer

(a) $(-3, -1)$
(b) $(-1, +\infty)$
(c) $(-\infty, -3)$

#### Work Step by Step

(a) The graph is rising from $x=-3$ to the $x=-1$. Thus, the function is increasing in the interval $(-3, -1)$.
(b) The graph is falling from $x=-1$ to the right. Thus, the function is decreasing in the interval $(-1, +\infty)$.
(c) The graph is constant (horizontal) from $x=-3$ to the left. Thus, the function is constant in the interval $(-\infty, -3)$.