The correct answer is "Stem changing verbs in the preterite normally change from o to ue or from e to ie"
example of o to ue
Almorzar "to eat lunch"
Yo almuerzo
tu/usted almuerzas
el/ella/usted almuerza
nosotros (doesn't change) almorzamos
ellos/ellas/ustedes almuerzan
example of e to ie
Querer " to want"
yo: quiero
tu: quieres
el/ella/usted:quiere
nosotros: (doesn't change) queremos
ellos/ellas/ustedes: quieren.
Hope this helps ;)