#### Answer

a) Limit exists (0).
b) Limit exists (-1).
c) Limit does not exist.
d) Limit exists (-1).

#### Work Step by Step

a) Limit exists. Function is not defined at t = -2, but it approaches to 0 from either side as t approaches to -2.
b) Limit exist. Function approaches to -1 from either side as t approaches to -1.
c) Limit does not exist. Function does not approach a single value from either side as t approaches to 0.
d) Limit exist. Function approaches to -1 from either side as t approaches to -0.5.