All content produced specifically to a Brief is fully owned (exclusive rights) by the Buyer as soon as it has been submitted to the job. This means that you can’t sell the content to anyone else. All rights have been transferred to the clinet.
If you do not wish to sell the exclusive rights to your content, you can't pitch your portfolio to those jobs where exclusive rights are required by the client.Remember, you need to make sure that your piece of content doesn't appear in any other archives (e.g.: stock websites, etc) as the clients pay for bespoke content. This is the only client you can sell the content to.