The PHP code is given below:
<h3>PHP code</h3>
if(isset($_REQUEST['login_btn'])){
$email = filter_var(strtolower($_REQUEST['email']),FILTER_SANITIZE_EMAIL); //strtolower changes email to all lower case
$password = strip_tags($_REQUEST['password']);
The remaining code is in the file attached.
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brainly.com/question/27750672
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The answer you're looking for might be "backwards-compatible".
Answer:
it changes the level of music, such as bass level or sweter level
A, because if not, there is nothing to say it exsists