In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: Unpublished reports were requested from the World Health Organization ( WHO ) and the Food and Drug Administration ( FDA ) .
### Output Text:
Unpublished reports were requested from the World Health Organization ( WHO ) and the Food and Drug Administration ( FDA ) . 