What would the output display for document.write("The temperature is "+81);?

The output from the code document.write("The temperature is "+81); would indeed display "The temperature is 81." This occurs because the document.write() function takes a string as an argument and outputs it to the web page.

In the provided code, the string "The temperature is " is concatenated with the number 81. JavaScript automatically converts the number to a string during this concatenation process. As a result, the two parts combine seamlessly, forming the complete sentence without any additional characters or symbols.

It's also important to note that the formatting options provided in other choices either omit key parts of the string or introduce unwanted characters. Thus, the correct choice reflects the complete message without errors or omissions.