Answer
a) Accelerates to the Right.
(b) Remains in place
(c) Accelerates to the Left
Work Step by Step
(a) Since the charge is positive, hence it will accelerate along the direction of the electric field.
(b) Since a neutral object is placed, hence $ F=qE=0$. So the object will remain where it is.
(c) Since the charge is negative, hence it will accelerate opposite the direction of the electric field.
Hence,
(a) Accelerates to the Right.
(b) Remains in place
(c) Accelerates to the Left
