AckTimeoutRetry Mechanism

Hi,

I would like to check AckTimeoutRetry is for class A or class C. According to stack, functionalities of AckTimeoutRetry is for class C only, but when i check LoRa vendor they told AckTimeoutRetry is for all classes.

Please confirm me AckTimeoutRetry is for Class A or Class C?
Also, is there any retries mechanism for class A.

Regards
Rohit