Which of the following disproportionation reaction

A disproportionation reaction is a reaction in which, the same element is simultaneously oxidized and reduced.

 $2H_2{O}_2\to 2H_{2}O+O_2$

In the above reaction, $H_2{O}_2$ is getting reduced to water, because the oxidation state of oxygen changes from −1 to −2, While that of $H_2{O}_2$ is also getting oxidized to oxygen  as the oxidation state of oxygen changes from −1 to 0.

Hence the correct option is (A).