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.
Jackie está tomando sol en la playa .
Mi primito juega con su bisicleta .
La chica patina hasta la casa de la abuela .
Los fines de semana tú juegas deportes con tus amigos.
You can do a list, watch your shows in Spanish w English subs or viceversa
The answer would be D) me duele la pierna
