function showreg(op) {
  document.getElementById('Advertising Inquiry').style.display='none';
  document.getElementById('Author Application').style.display='none';
  document.getElementById('Other Proposal').style.display='none';

  if (op == '') {
    document.getElementById('Contact').style.display="block";
    document.getElementById('Submit_Button').style.display="none";
  }
  if (op == 'Advertising Inquiry') {
    document.getElementById('Contact').style.display="none";
    document.getElementById('Advertising Inquiry').style.display="block";
    document.getElementById('Submit_Button').style.display="block";
  }
  if (op == 'Author Application') {
    document.getElementById('Contact').style.display="none";
    document.getElementById('Author Application').style.display="block";
    document.getElementById('Submit_Button').style.display="block";
  }
  if (op == 'Other Proposal') {
    document.getElementById('Contact').style.display="none";
    document.getElementById('Other Proposal').style.display="block";
    document.getElementById('Submit_Button').style.display="block";
  }
}