A locomotive approaches its next stop and accelerates at -0.12 m/s^2, coming to a complete stop in 30 seconds. This motion could best be described as positive velocity & positive acceleration
negative velocity & negative acceleration
positive velocity & negative acceleration
negative velocity & positive acceleration

positive velocity & negative acceleration

Explanation:

Accelerated Motion

Both the velocity and acceleration are vectors because they have magnitude and direction. When the motion is restricted to one dimension, i.e. left-right or up-down, the direction is marked with the sign according to some preset reference.

The locomotive is moving at a certain speed with a (so far) unknown sign but the acceleration has a negative sign. Since the locomotive comes to a complete stop it means the velocity and the acceleration are of opposite signs.

Thus the velocity is positive.

positive velocity & negative acceleration