Which of these is a spiral-horned antelope?
The addax ('Addax nasomaculatus'), also known as the white antelope, is an antelope of the genus 'Addax', that lives in the Sahara desert. It was first described by Henri de Blainville in 1816. They are sexually dimorphic, as the females are smaller than males. The colour of the coat depends on the season - in the winter, it is greyish-brown with white hindquarters and legs, and long, brown hair on the head, neck, and shoulders; in the summer, the coat turns almost completely white or sandy blonde.
The horns, which are found on both males and females, have two to three twists and are typically 55 to 80 cm (22 to 31 in) in females and 70 to 85 cm (28 to 33 in) in males, although the maximum recorded length is 109.2 cm (43.0 in). The lower and mid portions of the horns are marked with a series of 30 to 35 ring-shaped ridges. The tail is short and slender, ending in a puff of black hair. The hooves are broad with flat soles and strong dewclaws to help them walk on soft sand. All four feet possess scent glands. The life span of the addax is up to 19 years in the wild, which can be extended to 25 years under captivity.