The correct answer is D.
In fact, the gravitational force exerted by the massive object on the less-massive object is equal to the force exerted by the less-massive object on the massive object, and it is equal to
[tex]F=G \frac{m M}{r^2} [/tex]
where m is the mass of the less massive object, M the mass of the massive object, G the gravitational constant and r the distance between the two objects.
For Newton's second law, the force acting on each of the objects is the mass of the object times its acceleration:
[tex]F= M a_M[/tex]
[tex]F= m a_m[/tex]
So the accelerations of the two objects are:
[tex]a_M = \frac{F}{M} [/tex]
[tex]a_M = \frac{F}{m} [/tex]
we can see from the two equations that
1) the acceleration of the massive object, [tex]a_M[/tex], is very small because its mass M is big
2) the acceleration of the less-massive object, [tex]a_m[/tex], is larger because its mass m is smaller
Therefore there will be a net acceleration produced on the less-massive object (and on the massive object, but it will be negligible)