For peopled aged 5+ only.
21a. What language is most frequently used at home?
P21a. What language is most frequently used at home?
Read the question and wait for a reply. With this Question we intend to know the most frequently used language at HOME, whether or not they use other languages at school or work. Note that it is also correct if person states that at home they use one of the languages declared in P19 or P20.
Back to the example with Mr. Antônio, as we know he learned to speak in Echwabo, but at home the language he uses the most is Portuguese. Therefore, the language that id most frequently used at home is Portuguese.