It's a Pond Slider (Trachemys scripta) and is probably the more common subspecies, the Red Eared Slider (Trachemys scripta elegans). It's definitely not a Yellow Bellied Slider (Trachemys scripta scripta) and is most likely not a Cumberland Slider (Trachemys scripta troosti).
RES can vary a bit, but this does appear to be a RES indeed. This also looks like a large female, given the shape of her carapace.