Which of the Following Is the Key Advantage of Pre-Ejection

Which of the following is the key advantage of pre-ejection period (PEP) over interbeat interval (IBI) as a measure of cardiac activity?

A) IBI can only be measured with an x-ray or similar imaging, whereas PEP can be measured with sensors placed on the skin.
B) PEP is influenced only by emotional stress, whereas IBI can also be influenced by physical movement.
C) PEP is only influenced by sympathetic activation, whereas IBI is influenced by both sympathetic and parasympathetic activation.
D) Changes in PEP can be measured on a finer scale than changes in IBI.