You are developing a customer web form that includes the following HTML.
<input id=”txtValue”/>
You need to change the HTML markup so that customers can enter only a valid three-letter country code.
Which HTML should you use?

A.
<input id=”txtValue” type=”code” />

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

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

D.
<input id=”txtValue” type=”country” />

Explanation:
HTML <input> pattern Attribute
The pattern attribute specifies a regular expression that the <input> element’s value is checked against.
Example
An HTML form with an input field that can contain only three letters (no numbers or special characters):
<form action=”demo_form.asp”>
Country code: <input type=”text” name=”country_code”
pattern=”[A-Za-z]{3}” title=”Three letter country code”>
<input type=”submit”>
</form>
HTML <input> pattern Attribute
http://www.w3schools.com/tags/att_input_pattern.asp