Which HTML should you use?

You are developing a customer web form that includes the following HTML.
<input id=”txtValue” />
A customer must enter a value in the text box prior to submitting the form.
You need to add validation to the text box control.
Which HTML should you use?

A.
<input id=”txtValue” type=”text” required=”required”/>

B.
<input id=”txtValue” type=”text” pattern=”[A-Za-z]{3}” />

C.
<input id=”txtValue” type=”required” />

D.
<input id=”txtValue” type=”required” autocomplete=”on” />

Explanation:
We can ensure that a user has required a form fieldby adding the required attributelike this:
<label for=”name”>Name</label>
<input type=”text” name=”name” autofocus required id=”name”>
<input type=”text” name=”name” autofocus required=”required” id=”name”>