Aux verb for monter

Question

Why is it "Elle a monté" instead of "Elle est montée"?

Accepted Answer

Hi Beverly, 
This was in another text,
monter les escaliers
takes 'avoir'
Chris has answered your other posted query on the matter ...

Answer

Hi Beverly,I have listened several times but didn't hear monter being used, but did hear sortir.Both of these verbs can take either avoir or être depending upon the usage with a direct object or an indirect object.The two neighbours meet by chance as they are putting out for collection their waste bins. In the perfect, we can say " j'ai sorti les poubelles where les poubelles are the direct object therefore avoir as the auxiliary.Not sure if this helps you or not?Jim