Answers can include: lomg eyelashes and closing nostrils to protect from sand in the wind, large eyebrow ridge and thick eyebrows to protect from sun, thick fur to contain heat during cold nights, sandy colour for camouflage, large capacity for water to allow for water shortages, fat stored in hump to allow for food storage, wide feet for navigating loose sand.
Sexual reproduction and mutation creates variation in offspring. Those with unfavourable characteristics are less likely to reproduce, and those with favourable characteristics are more likely to pass on those favourable characteristics to offspring. Those offspring might then have favourable characteristics which continue to pass down.