What to do if I made a mistake in DS-160?

Rosa writes, "I did not fully understand the meaning of a question and selected the wrong answer.  In response to a question about being denied entry into the US, I said yes, even though I was only denied a visa of a different category.  Now I have a request for evidence (RFE) from the embassy asking for documentation related to denial of entry.  I am told that I cannot schedule a visa interview till I send the documents.  What should I do now?  How do I rectify the error?

You must write a letter in response to the RFE stating clearly what happened and how the confusion arose.  Keep it simple and write in bullet points.  Attach any evidence that you might have saved regarding your visa denial.  Hopefully, that should do it.  If not, you must file a new application.