0.dataobject.php

<?php
/**
 * mysite/code/SomeExtension.php
 *
 * @author Nathan J. Brauer http://NathanBrauer.com
 * @package SilverStripe-SomeExtension
 */
class SomeDataObject extends DataObject {

	static $extensions = array(
		'SomeExtension',
	);

	function MethodOptionA() {
		return "<p>Option <strong>A</strong></p>";
	}

	function MethodOptionB() {
		return "<p>Option <strong>B</strong></p>";
	}

}

1.extension.php

<?php
/**
 * mysite/code/SomeExtension.php
 *
 * @author Nathan J. Brauer http://NathanBrauer.com
 * @package SilverStripe-SomeExtension
 */
class SomeExtension extends DataExtension {

	function MethodOptionA() {
		$Data = $this->owner->MethodOptionA();
		return ($Data) ? strip_tags($Data) : false;
	}

	function MethodOptionB() {
		$Data = parent::MethodOptionB();
		return ($Data) ? strip_tags($Data) : false;
	}

}

2.result.php

<?php
$Some = new SomeDataObject;

//Which will work?

var_dump($Some->MethodOptionA());
// Option A

var_dump($Some->MethodOptionB());
// Option B

//Or is there a better way?