The highest display resolution of the VIZIO M49-C1 is 4K Ultra HD. That's over four times the display resolution of the most common HD type of Full HD. 4K Ultra HD TVs have a resolution of 3840 x 2160 pixels.
A 4K Ultra HD HD type is in fact the best display resolution across all similar spec TVs that came out around the same time as the M49-C1.
The worst display resolution amongst comparable types of TV is HD Ready.
4K Ultra HD TVs have a resolution of 3840 x 2160 pixels.