<form name="myform" action="git.php" method="POST">
<input type="radio" name="soru1" value="a"> A<br>
<input type="radio" name="soru1" value="b"> B<br>
<input type="radio" name="soru1" value="c"> C<br>
<input type="radio" name="soru1" value="d"> D<br>
<input type="button" value="gonder">
</form>

<?php
$cevap1 = $_GET[soru1];
if ($cevap1 == a) { echo "dogru cevap"; }
else { echo "yanlis cevap"; }
?>