Final answer:
The punctuation that sets an interjection off from the rest of the sentence is an exclamation point (!).
Step-by-step explanation:
The punctuation that usually sets an interjection off from the rest of the sentence is an exclamation point (!).
For example:
'What a mess!' she blurted out.
'Stop! That hurts!' he shouted.
Parentheses or commas are commonly used to set an interjection off from the rest of the sentence. The choice between parentheses and commas depends on the level of emphasis or interruption the interjection adds to the sentence. Parentheses tend to indicate a stronger separation or interruption, while commas are used for a milder interruption. For example:
Wow! That's incredible. (Stronger emphasis with exclamation and parentheses)
Well, I guess we can try again. (Milder interruption with a comma)