C. Abierto.
The past participle is the tense with -ed, but abrir is one of the irregulars.
Well, I can't help you write the whole essay, but if you want I can give you some tips!
500 i think , i dont get if its a question or statement
Answer:
Estudian
Explanation:
I am using the third person plural form (lost estudiantes) of estudiar in present tense.
El/ella/usted estudia
Ellos/ellas/ustedes estudian
Nosotros/as estudiamos
