The next place he’s going to do next is (Va a llegar a casa )
1. Nosotros entramos
2. Tu ayudas
3. Nosotros caminamos
4. El toca la guitarra
5. Ella enseña
6. Ellos esperan
7. Ellos estan cenando (I'm not sure about the exact translation of this one. I do speak spanish but this one doesn't really have a correct and exact translation)
8. Yo patino
9. Tu contestas/respondes
10. Yo llegue
A sneer has a negative connotation, as it's a scornful statement or tone. Rosy can have a bit positive connotation (to look at something through the rose-colored glasses), tennis shoes and powerhouse are totally neutral words.
First of all, it's important to note whether the sentence is referring to plural or singular noun. It mentions "los tratamientos", therefore it is plural which eliminates A and B.
Second of all, the phrase "es dudoso que..." is commonly associated with subjunctive. Curar is the original form of the word which in subjunctive changes ar to er tenses.
Therefore your answer is C. curen because it is both subjunctive and plural
