Kemija - 2013./14. ljeto - 33.

A. ${\mathrm{O}\mathrm{H}}^{-}\backslash mathrm\{OH\}^\{-\}$

B. ${\mathrm{H}}_2{\mathrm{C}}_2{\mathrm{O}}_4\backslash mathrm\{H\}\_\{2\}\; \backslash mathrm\{C\}\_\{2\}\; \backslash mathrm\{O\}\_\{4\}$

C. ${\mathrm{C}\mathrm{O}}_2\backslash mathrm\{CO\}\_\{2\}$

D. ${\mathrm{C}}_2{\mathrm{O}}_4{}^{2-}\backslash mathrm\{C\}\_\{2\}\; \backslash mathrm\{O\}\_\{4\}\{\; \}^\{2-\}$