Which artery carries deoxygenated blood instead of oxygenated blood?

$A$: The cardiac impulse which originates from $SA$ node in mammalian heart cannot spread directly from atria to ventricles.
$R$: In mammalian heart there is no continuity between cardiac muscle fibres of atria and those of ventricles except $AV$ bundles.

The first heart sound is

Assertion : $Lub$ is a heart sound which is produced during each cardiac cycle.
Reason : It is associated with the closure of the tricuspid and bicuspid valves.

Assertion : Muscle fibres of $SA$ node possess the lowest rhythmicity among all cardiac muscles.
Reason : Due to this fact,it can initiate excitatory waves at the highest rate.

What is the heart rate of children compared to adults?