Which of the following statements is true about endl in C++?

In C++, the statement that endl indicates the end line is accurate because endl is a manipulator used specifically in output streams like cout. When used in a program, it produces a newline character, which causes the output to jump to the beginning of the next line, thus defining the end of the current line of text output. This function not only moves the cursor to the next line but also flushes the output buffer, which ensures that all output operations are completed immediately.

The other options are not true. A tab character is represented by the escape sequence '\t', and it serves a different purpose than endl. The phrase "end of the program" does not relate to endl, as it pertains to program termination rather than output formatting. Declaring a variable involves providing a type and a name, which has no relation to endl’s functionality. Thus, the correct choice effectively highlights the primary role of endl in C++.