Answer
Improper: $B,C$ and $D$
Work Step by Step
If the domain or range of the integrated portion approach infinity, then it is an improper integral.
(a) The domain and range never approach infinity (tangent is defined in the interval). This can be seen by graphing.
(b) $\lim\limits_{x \to \pi/2} tan(x) = $Does not exist
the range goes to $\pm\infty$, therefore B is improper.
(c) The function is discontinuous at x=-1, which is part of the interval. Therefore, C is improper.
(d) The domain goes to $\infty$, therefore D is improper.
