How should the developer modify the data layer?

A developer needs to add the broweser referrer value to the page data layer. No developer resources are available to make the change on the page. The developer needs to use DTM to include the page referrer without changing the actual source code.

How should the developer modify the data layer?
A . Use a page load rule that executes at top of page to add the ‘digitalData.page.pageReferrer’ attribute to the data layer within DTM after the _satellite pageBottom() function fires.
B . Call a data element that contains the browser referrer at page bottom. Add the "digitalData.page.pagerefferer" attribute to the data layer within DTM to include the value of the data element.
C . Create an event based rule to set the data layer with the value of the referrer.
D . Set a cookie at page bottom that contains the browser referrer (if it exists). Use a direct call rule to set the data layer in DTM with the value of the cookie.

Answer: D