What will be the output of the following PHP code?

<?php
function b()
{
    echo "b is executed";
}
function a()
{
    b();
    echo "a is executed";
    b();
}
a();
?>

A. b is executedb is executedb is executed

B. b is executeda is executed

C. a is executed

D. b is executeda is executedb is executed

Answer: Option D