Respuesta :
Answer:
B = habían oido
This question is not about anyone else but Mariana. Nobody else is involved so A and C will not fit into the statement. The correct answer is B, which would be "Mariana habían oido el chiste hace dos semanas."
C. Había oído
The statement is singular for one person the word había states that she heard it in the past for example 2 weeks ago
The statement is singular for one person the word había states that she heard it in the past for example 2 weeks ago