The cardiac output increases with an increase in all of the following, except

Cardiac output is the product of stroke volume and heart rate and hence cardiac rate would increase with an increase of either stroke volume or heart rate. Venous return refers to the flow of blood back to the right atrium. Under steady-state conditions, venous return equals cardiac output over a given period of time.

Increase in the duration of cardiac cycle would decrease the heart rate and thereby the cardiac output.