In the reaction of sulphur dioxide and hydrogen sulphide, identify the reducing agent and choose it.

The correct option is B Hydrogen sulphide
The reaction between sulphur dioxide and hydrogen sulphide is as follows:

$S{O}_2+2H_{2}S\to 2H_{2}O+3S$

From this reaction we can see that $S{O}_2$ is getting reduced i.e., oxygen atoms are removed which indicates that $S{O}_2$ is an oxidising agent.
Whereas $H_{2}S$ is getting oxidised i.e., removal of hydrogen. So, $H_{2}S$ is a reducing agent.