How is the regulation of cardiac activity performed?

How do parasympathetic neural signals affect the working of the heart?

Read the following statements:
$I$ - Increased heart rate.
$II$ - Increased ventricular contraction force.
$III$ - Decreased cardiac efficiency.
$IV$ - Increased cardiac efficiency.
$V$ - Decreased heart rate.
$VI$ - Decreased conduction speed of action potential.
Categorize the given statements into Sympathetic and Parasympathetic nervous systems.
Sympathetic Nervous System $\quad$ Parasympathetic Nervous System

When a normal heart is injected with a physiological concentration of adrenaline,it shows:

Heart is innervated by

Which of the following factors increase the heart rate?
$(A)$ Sympathetic nerve signals
$(B)$ Parasympathetic nerve signals
$(C)$ Adrenal medullary hormones
$(D)$ Vagus nerve
$(E)$ Thyroxine hormone
$(F)$ Acetylcholine