Bats belong to which order?

The only poisonous mammal is:

Assertion $(A)$: Cold-blooded animals do not have a fat layer.
Reason $(R)$: Cold-blooded animals use their fat for metabolic processes during hibernation.

Which of the following mammals is adapted for aerial life?

Which one of the following is different from the others?

$A$: In metatherians,the scrotum is present in front of the penis.
$R$: In prototherians,the scrotum is present behind the penis.