La asociación de estudiantes organizó un baile de fin de curso.
The correct option is option D because it is the only one that fits, because the subject of the sentence is "él/ella" (he or she).
The present perfect simple of the indicative of the verb "organizar" (to organize):
- Yo organicé
- Tú organizaste.
- Usted organizó
- Él/Ella organizó
- Nosotros/as organizamos
- Vosotros/as organizasteis
- Ustedes organizaron
- Ellos/as organizaron
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