I think all the words described mean "room" but each has a slightly different meaning. - La habitacion is a room in a house usually. - El dormitorio is bedroom, like a college dormitory room, or dormir (sleep). - La sala is more like a living room or gathering space. A family room or living room is also called a salon or parlor. Also used for classrooms and public spaces. - El cuarto is more useful for describing a living space like a hotel room or apartment/flat. (is my understanding)
Cuarto is correct but you have used it as a feminine word where it should be masculine i.e El cuarto. Duolingo marks it as wrong if you use the wrong gender and gives you the alternative word with the gender you have used in your answer. So technically you were correct but just be careful with the use of El and La.
room has a wide set of applications. A prefix generally specify the use, but they all are rooms. One of the meanings is the compartment of a house/apartment, this is exactly one of the meanings of cuarto.. Other translations could be good from a generic (cuarto-room) to a specific (sala/living room, dormitorio/bedroom, bathroom/cuarto de baño) or other generic like camara/chamber that is a delimited empty space. Duo should recognize it all as not wrong translations.
Confused.....I put La cuarto and have been told it should have been La recamara. Not even seen this word before and it isn't in my dictionary. Can anyone shed some light.......and what was wrong with cuarto anyway, was it just because I put it as a feminine word instead of masculine?
Here is a very good dictionary:
This is a great resource: https://www.google.com/ It has montones de informacion.