To answer this question, let's go through each option to understand why it is correct or incorrect:
Option A) echo() - This option is incorrect because the echo() function does not return a value. It simply outputs the given string or variable to the browser or console.
Option B) print() - This option is correct because the print() function outputs the given string or variable to the browser or console, and returns a value of 1 if the output is successful.
Option C) both - This option is incorrect because only the print() function returns a value of 1 when the output is successful. The echo() function does not return a value.
Option D) none - This option is incorrect because the print() function does return a value of 1 when the output is successful.
Therefore, the correct answer is B) print(). This option is correct because the print() function returns a value of 1 when the output is successful.