Answer:
the new gravitational force between the two masses is
of the original force (third option in the provided list)
Explanation:
Recall the expression for gravitational force :
, where
and
are the point masses, d the distance between them, and G the universal gravitational constant.
I our problem, the distant between the particles stays unchanged, and we need to know what happens with the magnitude of the force as mass A is tripled, and mass B is halved.
Initial force expression: 
Final force expression: 
Where we have recognized the expression for the initial force between the particles, and replaced it with
to make the new relation obvious.
Therefore, the new gravitational force between the two masses is
of the original force.