Which of these birds is a flightless duck species?

The Fuegian steamer duck ('Tachyeres pteneres') or the Magellanic flightless steamer duck, is a flightless duck native to South America. It belongs to the steamer duck genus 'Tachyeres'. It inhabits the rocky coasts and coastal islands from southern Chile and Chiloé to Tierra del Fuego, switching to the adjacent sheltered bays and lakes further inland when breeding.

This is the largest of the steamer duck species. It is a massively built waterfowl at 3.5–7 kg (7.7–15.4 lb) and 65–84 cm (26–33 in) in length, with the males noticeably larger than the females. Males weigh an average of 5.34 kg (11.8 lb) while females weigh around 4.2 kg (9.3 lb) on average. The wingspan is 85–110 cm (33–43 in), the wings being too small to functionally allow the birds to take flight. Instead, the wings are used like paddles to help skim rapidly across the surface of the water.