The answer is este it is used as a masculine adjective where as esto is a demonstrative pronoun for masculine and feminine nouns
The correct answer is the third one. "HAY muchos problemas en el mundo."
1-Es argentino
2-Es puertorriqueño
3-Somos dominicanos
4-Son chilenas
5-Soy mexicano
6-Es guatemalteca
7-Son panameños
8-Es peruana
9-Son cubanos
10-Soy colombiano
11-Es costarricense
12-Soy americano
True. Her last concert was at the Houston Astrodome
