Hello!

The subject of this sentence is "Yo" (I), so we must use the first-person singular conjugation.
Thus, the correct conjugation ends with an "o", or "Pruebo". Choice A is the correct answer.
What words? What pictures?
Answer:
Not sure about the 2nd one, but here are the rest.
3. Hace la tarea.
4. Dale comida.
5. Quita el polvo.
6. Arregla el dormitorio.
7. Escribe tú nombre.
8. Abre la ventana.
9. Aprende el vocabulario nuevo.
10. Come la cena.
Hope this helped.
Do you have a picture of the problem