C. Abierto.
The past participle is the tense with -ed, but abrir is one of the irregulars.
Igualmente because If u translate it “mucho gusto” is basically “nice to meet you” and “igualmente” means “you too” or in this case “nice to meet you too” which makes sense.
La forma correcta de aprender es aprendo.
La oracion correcta ed yo aprendo bien en clase.