Anwers are:

(a)    The object is moving in the positive direction and slowing down. The acceleration is opposite to the velocity, i.e. negative.

(b)    The object is moving in the negative direction and slowing down. The acceleration is opposite to the velocity, i.e. positive.

(c)    The object is moving in the negative direction and speeding up. The acceleration is parallel to the velocity, i.e. negative.

(d)    The object is moving in the positive direction and speeding up. The acceleration is parallel to the velocity, i.e. positive.