How to make a checklist with exactly 1 or 2 possible boxes checked in HTML [duplicate]

I need to make a checklist in HTML, but I need to have only 1 or 2 possible boxes checked. I can use JavaScript if necessary.

Here is my code:

<ul>
  <li><input type="checkbox">Option 1</li>
  <li><input type="checkbox">Option 2</li>
  <li><input type="checkbox">Option 3</li>
  <li><input type="checkbox">Option 4</li>
  <li><input type="checkbox">Option 6</li>
  <li><input type="checkbox">Option 7</li>
</ul>

Any help would be greatly appreciated.