Final answer:
Option (a), According to the Frank-Starling relationship, increased sympathetic stimulation results in a greater stroke volume due to increased contractility and a decrease in end-systolic volume after a forceful contraction of the heart.
Step-by-step explanation:
According to the Frank-Starling relationship, for any given end-diastolic volume (EDV), increased sympathetic stimulation will result in greater stroke volume (SV). This is because sympathetic stimulation to the venous system will increase venous return, contributing to ventricular filling and thereby EDV and preload.
When preload increases, ventricular muscle fibers are stretched more optimally before contraction, which according to Starling's law of the heart, leads to a more forceful contraction. This increased contractility results in a greater SV by ejecting more blood during systole and, consequently, a smaller end-systolic volume (ESV).
Ventricular ejection phase occurs during the second phase of ventricular systole, in which the ventricles contract and eject blood into circulation. A stronger contraction, enhanced by sympathetic stimulation, will effectively reduce the volume of blood left in the ventricle at the end of systole (ESV) and increase the volume of blood ejected (SV).
Therefore, the correct answer is a) greater stroke volume.