Question

ar preterit
yo é nosotros/as amos
tú aste vosotros/as asteis
él/ella/usted ó ellos/ellas/ustedes aron
¿______ (cantar) ustedes?
cantaron
cante
canto

Explanation:

The question asks to conjugate the -AR verb cantar (to sing) in the preterite tense for the subject ustedes (formal plural "you"). Using the provided preterite -AR verb chart, the ending for ustedes/ellos/ellas is aron. Removing the -AR stem from cantar leaves cant-, so combining the stem and ending gives the correct conjugated form.

Answer:

cantaron