Given the structures of maleic acid and fumaric acid, which statement correctly describes their configurations?

• A. Both maleic acid and fumaric acid have trans configurations.
• B. Maleic acid has a cis configuration, and fumaric acid has a trans configuration.
• C. Maleic acid has a trans configuration, and fumaric acid has a cis configuration.
• D. Both maleic acid and fumaric acid have cis configurations.

Answer: (B)