Final answer:
The Python code to display "Hello, world!" is 'print("Hello, world!")'. It uses the print function with the text enclosed in quotation marks.
Step-by-step explanation:
The Python code segment that will display "Hello, world!" on the screen is 2) print "Hello, world!". In Python, the print function is used to output text to the console. The correct syntax involves using the print statement followed by the text you want to display, enclosed in quotation marks. Here's how you would write it:
print("Hello, world!")
It is important to use the quotation marks to indicate that "Hello, world!" is a string, a type of data in Python that represents text.