A store sells shirts only in small, medium, and large sizes, and only in red, yellow, and blue colors. Casey buys exactly three shirts from the store.
A shirt type consists of both a size and a color.
Casey does not buy two shirts of the same type.
Casey does not buy both a small shirt and a large shirt.
No small red shirts are available.
No large blue shirts are available.
If Casey buys a small blue shirt, which one of the following must be false?