JSFiddle - React, Tailwind, and code Playground

HTML

<body>
<select class="poli" data-val="true" data-val-number="The field politicusId1 must be a number." data-val-required="Je moet minimum één politicus selecteren" id="politicusId1" name="politicusId1" style="display:inline-block">
    <option value="">- Kies een politicus -</option>
    <option value="2">Vera Celis</option>
    <option value="3">Frank Creyelman</option>
    <option value="4">Steve D&#39;Hulster</option>
    <option value="5">Dirk de Kort</option>
</select>
<select class="poli" data-val="true" data-val-number="The field politicusId2 must be a number." data-val-required="The politicusId2 field is required." id="politicusId2" name="politicusId2">
    <option value="">- Kies een politicus -</option>
    <option value="2">Vera Celis</option>
    <option value="3">Frank Creyelman</option>
    <option value="4">Steve D&#39;Hulster</option>
    <option value="5">Dirk de Kort</option>
</select>
<select class="poli" data-val="true" data-val-number="The field politicusId3 must be a number." data-val-required="The politicusId3 field is required." id="politicusId3" name="politicusId3">
    <option value="">- Kies een politicus -</option>
    <option value="2">Vera Celis</option>
    <option value="3">Frank Creyelman</option>
    <option value="4">Steve D&#39;Hulster</option>
    <option value="5">Dirk de Kort</option>
</select>
<select class="poli" data-val="true" data-val-number="The field politicusId4 must be a number." data-val-required="The politicusId4 field is required." id="politicusId4" name="politicusId4">
    <option value="">- Kies een politicus -</option>
    <option value="2">Vera Celis</option>
    <option value="3">Frank Creyelman</option>
    <option value="4">Steve D&#39;Hulster</option>
    <option value="5">Dirk de Kort</option>
</select>
<select class="poli" data-val="true" data-val-number="The field politicusId5 must be a number." data-val-required="The politicusId5 field is required." id="politicusId5" name="politicusId5">
    <option...

JavaScript

$('.poli').on('keyup change', function () {
    $(this)
        .siblings('select')
        .children('option[value=' + this.value + ']')
        .attr('disabled', true)
        .siblings().removeAttr('disabled');
});