JSFiddle - React, Tailwind, and code Playground

HTML

<select name="blend1" id="blend1">
  <option value="1">1</option>
  <option value="2">2</option>
  <option value="3">3</option>
  <option value="4">4</option>
  <option value="5">5</option>
  <option value="6">6</option>
  <option value="7">7</option>
  <option value="8">8</option>
</select>

<select name="gtype1" id="gtype1">
  <option value="1">1</option>
  <option value="2">2</option>
  <option value="3">3</option>
  <option value="4">4</option>
  <option value="5">5</option>
</select>

JavaScript

$('#blend1').on('change', function(e) {
	var checkOn = ['5', '6', '7', '8'];
  
	if (checkOn.indexOf($(this).val()) > -1) {
     $("#gtype1 option[value='1']").attr('disabled',true);
     $("#gtype1 option[value='3']").attr('disabled',true);
	} else {
    $("#gtype1 option[value='1']").attr('disabled',false);
    $("#gtype1 option[value='3']").attr('disabled',false);
	}
});