the answer is A. Imperfecto progresivo.
The progressive imperfect is used to express something that was taking place in the past. It is formed using the verb to be in past (in this case: estaba) plus the verb ending in ing (ando, endo, in this case: cantando). It is mainly used for: on-going actions that were happening in the past.
Well id have too see the blog post and the video too help out i'm fluent in spanish so id be able to help out :)
El vecino del a lado construye edificios pero no es carpintero. “Es un ingeniero”
Francisco pays for the clothes in the store with pesos...He is in Mexico
