A is your answer . El cuello
I think they only have 2 levels sorry if this isn't right!
- Servir ⇝ Sirva

You only have to remove the <u>direct object</u> that is added to the verb. The verb must not have the direct object.
<h3><em><u>MissSpanish</u></em></h3>
Answer:
1) Nosotros estamos comiendo
2) Yo estoy abriendo la vantana
3) Mirta esta leyendo un libro
4) los estudiantes estan aprendiendo