The statement that best explains how Kumalo’s reaction develops the theme that racism can divide and destroy a society is:
Kumalo’s tears at witnessing such cooperation indicates that he is not used to seeing people of different races work together.
This response highlights Kumalo's surprise and emotional reaction to the solidarity between people of different races, illustrating how the deep-rooted racism in society has created divisions that have made such cooperation rare. His tears symbolize hope and the possibility of unity, contrasting with the destructive nature of racism that has historically separated people.