Using the imperfect tense in Spanish to "describe" a situation in the past

Question

Can someone please tell why is it Los padres paseaban con sus hijos por el parque.instead of Los Padres estaban paseando con sus hijos por el parque.Por favor ayudarme! :)

Accepted Answer

Hola Punya
If you follow literally the translation in English here:
Los padres ___ con sus hijos por el parque. (Parents were walking with their children in the park.)  Hint: It is describing a situation 
you would say "estaban paseando" as you suggested, and that is absolutely correct. 
However, this question is a dropdown menu question where you need to choose one of the options given. In that case, as it's not presenting the progressive tense on the menu (estaban paseando), the only possible option for a "descriptive situation in the past" as the hint is indicating, would be the imperfect tense of the verb pasear: "paseaban".
The imperfect tense and the imperfect progressive are very similar in the sense that they both describe "what was happening", with the progressive being more literal as it uses estar + present participle, and the imperfect being less literal, it is simply that tense's nuance, as the lesson is explaining.
I hope that clarified it for you. 
Un saludo
Inma