Answer
The correct acceleration vector is H.
Work Step by Step
The particle is slowing down. Therefore, the component of the acceleration vector which is parallel to the particle's velocity vector must point in the opposite direction from the velocity vector.
The particle is curving upward. Therefore, the component of the acceleration vector which is perpendicular to the particle's velocity vector must point upward.
The acceleration vector points upward and to the left. The correct acceleration vector is H.
