Final answer:
The contribution of venous return to cardiac output includes regulation of blood pressure, heart rate control, stroke volume adjustment, and blood oxygenation.
Step-by-step explanation:
Cardiac output is the volume of blood pumped by the heart in one minute, and it can be influenced by several factors. When it comes to the contribution of venous return to cardiac output, all the options mentioned in the question are correct. Regulation of blood pressure, heart rate control, stroke volume adjustment, and blood oxygenation all play a role in determining cardiac output. For example, regulating blood pressure can affect stroke volume by influencing the resistance of blood flow, while heart rate control can directly impact the number of heart contractions per minute and therefore affect cardiac output.