Itemize NET Developer interview questions

The interview process for me began with a brief phone screen and then a programming assignment. The assignment was to write a Web API in which I was to choose the technologies which included the language and the database. I spent about 3 days developing this API, documented it and provided a testing tool. After delivering the solution, I received an email the next day which simply said they decided not to move forward without any explanation as to how they came to this decision. If someone makes an effort to deliver a product and spends a good amount of time to put it together, they at least deserve some explanation so that they can better understand and learn from the experience. Instead, I got this email with no explanation, it's simply RUDE!