Repeating a denial doesn't make it so... I am forced to call this:
First, the claim was that he discriminated against blacks. That he used the "C" to do this is as ancillary as it is documented. After all, writing a "C" on someone's application is hardly noteworthy much less illegal, unless there's a deeper meaning to it, which there was. First, last and most importantly, he discriminated against blacks in providing housing and had to pay a fine, even though he never admitted to it.
But from the articles, which you have apparently not read:
first article said:
Trump Employees Marked Applications Of Minorities With Codes And Allegedly Directed Blacks And Puerto Ricans Away From Buildings With Mostly White Tenants. According to Washington Post, “Federal investigators also gathered evidence. Trump employees had secretly marked the applications of minorities with codes, such as ‘No. 9’ and ‘C’ for ‘colored,’ according to government interview accounts filed in federal court. The employees allegedly directed blacks and Puerto Ricans away from buildings with mostly white tenants, and steered them toward properties that had many minorities, the government filings alleged.” [Washington Post, 1/23/16]
I did make the mistake that the first article quoted the second article. So a quote from it would read the very same as the first quote.
third article said:
In the federal lawsuit, a superintendent for a Trump building in Cincinnati told the Justice Department that he was instructed by Trump managers to attach a “C” for “colored” to all applications from blacks.