Where are the PDFs hosted? If they're available via a URL, you can use JavaScript to dynamically link to them.
Here's an example, assuming you have two radio button fields for your options (given the option1 and option2 CSS classes).
$(document).ready(function () {
$('.option1').change(function () {
if ($(this).find('input:checked').val() == "Yes") {
$('<p class="link1"><a href="www.google.com">This is a test</a></p>').insertAfter(this);
} else {
$('.link1').remove();
}
});
$('.option2').change(function () {
if ($(this).find('input:checked').val() == "Yes") {
$('<p class="link2"><a href="www.google.com">This is a test</a></p>').insertAfter(this);
} else {
$('.link2').remove();
}
});
});
For each option's block of code, you'll update this line with the correct PDF location and link text:
$('<p class="link1"><a href="www.google.com">This is a test</a></p>').insertAfter(this);
You could use Workflow to send the correct PDF as an email attachment.