Pedro was born in chile. how would he tell someone his national origin? yo soy chilena. son chilenas. son chilenos. yo soy chileno.

First, Pedro is a guy (guy = chico). So of course, his nationality would end by "o" not "a", so it's either Son Chilenos, either Yo soy Chileno.
Since Pedro is only one person, So his nationality shouldn't end by "s".
We still got one choice: Yo Soy Chileno. "Yo" can be removed too, and simply say "Soy Chileno".

Hope this Helps! :)

3. study 4.eat 5.play american football 6.write a card 7.practice piano 8.swim in the pool 9.paint a mural 10.listen to the band 11.dance at a party 12.drink milk 13.visit panama 14.open the card 15.prepare dinner 16.stay in the house 17.watch tv 18.write on the paper 19.study spanish 20.examine the paintings in the museum. i hope this : )