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

Assertion $(A) :-$ Parasympathetic neural signals decrease the cardiac output.
Reason $(R) :-$ Parasympathetic neural signals decrease the rate of heartbeat and the speed of conduction of action potentials.

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

If the sympathetic nerve to the heart is cut off,the heart beat will

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:

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