Your question states: "Which of the following are valid arguments for an SNS Publish request?"
A REQUEST. https://docs.aws.amazon.com/sns/latest/api/API_Publish.html
The only valid arguments for a Publish REQUEST are:
You say: The correct answers are: Subject, MessageId, Timestamp
And your answer has a screen cap from AWS.
But this is a Publish CONFIRMATION return message. That's totally different.
A publish request couldn't have a messageId or Timestamp as an argument (An argument is a parameter I send to my SNS topic to publish a message). The messageId and timestamp are data points that SNS creates and returns to me in a confirmation message.
I hope I'm making myself clear. Please fix this question ASAP.