If the particle is located slightly to the left of point B, its acceleration is .
1 directed to the right
2 directed to the left
3 equal to zero

(1) directed to the right

Explanation:

To the right of B, u(x) is a decreasing function & so its derivative is negative,this implies that the x component of the force on a particle at this position is positive,or that the force is directed towards right .Small deviations from equilibrium at point B causes a force to accelerate the particle away ,hence particle is in unstable equilibrium.

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