Check out example codes for "how to choose multiple option from select option". It will help you in understanding the concepts better.

Code Example 1

<!-- JUST ADD multiple ATTRIBUTE WITHIN select ATTRIBUTE -->
Cars:<br>
<select name="car" multiple>
    <option value="Volvo">Volvo</option>
    <option value="Thar">Thar</option>
    <option value="Audi">Audi</option>
</select>

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