An art collection on auction consisted of 4 Dalis, 5 van Goghs, and 6 Picassos. At the auction were 5 art collectors. If a reporter noted only the number of Dalis, van Goghs, and Picassos acquired by each collector, how many different results could have been recorded if all of the works were sold?

The answer in my book is 8C4 x 9C4 x 10C4. But I don't understand why. Can anyone help to explain? Thanks.