According to the starling law, effects on cardiac rate and contractility include decreasing the rate of contraction and increasing the filling time resulting in a stronger contraction.

According to the starling law, parasympathetic effects on cardiac rate and contractility include decreasing the rate of contraction and increasing the filling time resulting in a stronger contraction.
The Frank-starling law of the heart states that the stroke volume of the heart increases in response to an increase in the volume of blood filling the heart when all other factors remain constant.

Parasympathetic is your answer