When calling an API operation on an EC2 Instance, the following error message was returned.
A client error (UnauthorizedOperation) occurred when calling the RunInstances operation:
You are not authorized to perform this operation. Encoded authorization failure message:
oGsbAaIV7wlfj8zUqebHUANHzFbmkzILlxyj__y9xwhIHk99U_cUq1FIeZnskWDjQ1wSHStVfdCEyZILGoccGpC
iCIhORceWF9rRwFTnEcRJ3N9iTrPAE1WHveC5Z54ALPaWlEjHlLg8wCaB8d8lCKmxQuylCm0r1Bf2fHJRU
jAYopMVmga8olFmKAl9yn_Z5rI120Q9p5ZIMX28zYM4dTu1cJQUQjosgrEejfiIMYDda8l7Ooko9H6VmGJX
S62KfkRa5l7yE6hhh2bIwA6tpyCJy2LWFRTe4bafqAyoqkarhPA4mGiZyWn4gSqbO8oSIvWYPwea
KGkampa0arcFR4gBD7Ph097WYBkzX9hVjGppLMy4jpXRvjeA5o7TembBR-Jvowq6mNim0
Which of the following can be used to get a human-readable error message?

Answer options:

A.Use the command aws sts decode-authorization-message.
B.Use the command aws get authorization-message.
C.Use the IAM Policy simulator, enter the error message to get the human readable format.
D.Use the command aws set authorization-message.

Answer – A
This is mentioned in the AWS Documentation.
Decodes additional information about the authorization status of a request from an encoded message returned in response to an AWS request.
For example, if a user is not authorized to perform an action that he or she has requested, the request returns a Client.UnauthorizedOperation response (an HTTP 403 response). Some AWS actions additionally return an encoded message that can provide details about this authorization failure.
Because of the right command used in the documentation, all other options are incorrect.
For more information on the command, please refer to the below URL-
https://docs.aws.amazon.com/cli/latest/reference/sts/decode-authorization-message.html