The most appropriate question to ask if you see a person sleeping in Spanish would be: "¿Estás cansada?" (if you're addressing a woman) or "¿Estás cansado?" (if you're addressing a man).
The other options are not correct in the given context:
- "Están cansada?" is incorrect because it uses the plural form "están" but refers to a singular person.
- "¿Estáis cansada?" is incorrect in this context unless you are addressing multiple people in a familiar way, and it also incorrectly uses the feminine form when referring to a mixed or male group.
So, stick with "¿Estás cansada?" or "¿Estás cansado?" depending on the gender of the person.