JavaScript

console.log('$(t).html()');
console.log($(t).html());
let a = parseFloat($(t).html());
console.log('a');
console.log(a);

<ul>
    <li>
        <label><input type="checkbox" name="a"> A</label>
        <ul>
            <li><label><input type="radio" name="opta" value="1"> Position 1</label></li>
            <li><label><input type="radio" name="opta" value="2"> Position 2</label></li>
            <li><label><input type="radio" name="opta" value="3"> Position 3</label></li>
        </ul>
    </li>
    <li>
        <label><input type="checkbox" name="b"> B</label>
        <ul>
            <li><label><input type="radio" name="optb" value="1"> Position 1</label></li>
            <li><label><input type="radio" name="optb" value="2"> Position 2</label></li>
            <li><label><input type="radio" name="optb" value="3"> Position 3</label></li>
        </ul>
    </li>
    <li>
        <label><input type="checkbox" name="a"> C</label>
        <ul>
            <li><label><input type="radio" name="optc" value="1"> Position 1</label></li>
            <li><label><input type="radio" name="optc" value="2"> Position 2</label></li>
            <li><label><input type="radio" name="optc" value="3"> Position 3</label></li>
        </ul>
    </li>
</ul>

let updateOptions = () => document.querySelectorAll("input[type='checkbox']").forEach(chk => {
    // Find the containing list item:
    let li = chk.closest("li");
    
    // Iterate over the radiobuttons in the same list item:
    li.querySelectorAll("input[type='radio']").forEach(rbn => {
        // If the checkbox is not checked, no position can be selected:
        if (!chk.checked){
            rbn.disabled = true;
            rbn.checked = false;
            return;
        }
        
        // If the same position is selected for any previous option, it cannot be selected:
        let value = rbn.value;
        let prevLi = li.previousElementSibling;
        while (prevLi !== null){
            var prevRbn = prevLi.querySelector(`input[type='radio'][value='${value}']`);
            if (prevRbn?.checked){
                rbn.disabled = true;
                rbn.checked = false;
                return;
            }
            
            prevLi = prevLi.previousElementSibling;
        }
        
        // This position can be selected:
        rbn.disabled = false;
    });
});

document.querySelectorAll("input[type='checkbox'], input[type='radio']").forEach(el => el.addEventListener("click", updateOptions));
updateOptions();