Why the McAfee licensing requirement in the terms and conditions for Reader?

I'm getting notifications to update my Adobe Reader XI. I clicked on the update, which brought up a box I had to check for the Terms and Conditions. In the terms and conditions, it says that you have to agree to McAfee licensing. Does agreeing to that mean that I will be required to purchase McAfee virus products to run the Reader software? Can someone explain why the McAfee licensing is required and what it actually is? Thanks.