Beginning with question #5, the form starts asking for explicit details about each person living at the location. The exact working is "Please provide information..."
The way I see it, you only have to answer the one question that is constitutional (for purposes of congressional apportionment). Everything else on the form is merely a request for optional information.
In other words, simply put "1" or "2" or "4" or whatever, and send the census form back without putting down any more information than what the government is supposed to collect.
Although if you wish to have some fun with it, I suppose one could put down "Klingon" as their race.