This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Cardiovascular system, Subject name: Physiology
All of the following factors normally increase the length of the ventricular cardiac muscle fibers except 
Select and explain. 
A. Increased venous tone, B. Increased total blood volume, C. Increased negative intrathoracic pressure, D. Lying to standing change in posture
D: Lying to standing change in posture
Answer: D: Lying to standing change in posture 
Explanation: Heteromeric regulation of stroke volume includes factors that regulate cardiac output as a result of changes in cardiac muscle length. End-diastolic volume has a role increasing the length of cardiac muscle fibres. .Venous return and ventricular filling are the factors affecting EDV. Venous return is affected by skeletal muscle pump, venous tone, negative intrathoracic pressure due to its suckinv effect, lying down posture than standing posture, increased blood volume. Ref: Textbook of medical physiology by N Geetha, 2nd edition, page no. 169,170