What is the effect on the heart rate if the parasympathetic nerve is cut in a rabbit?

Cardiac activities of the heart are regulated by:
$A.$ Nodal tissue
$B.$ $A$ special neural centre in the medulla oblongata
$C.$ Adrenal medullary hormones
$D.$ Adrenal cortical hormones
Choose the correct answer from the options given below:

An increase in blood flow to the atria of the heart can cause the release of ............ and it causes ............ in blood vessels.

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

Innervation of heart in the intact animals is primarily meant for

What is the effect of the parasympathetic nervous system on the heart rate?