The correct answer is C. English and French.
The working languages of UNESCO are English and French. This means that all official documents of UNESCO are published in both English and French. Meetings of UNESCO are also conducted in both languages.
English and French were chosen as the working languages of UNESCO because they are the two most widely spoken languages in the world. This ensures that all member states of UNESCO can participate in the organization’s activities.
The other options are incorrect because they do not include both English and French. Option A is incorrect because it only includes French. Option B is incorrect because it only includes English. Option D is incorrect because it includes English, French, and Russian. Russian is not a working language of UNESCO.