SpanishDict Quiz wrong answer?? (ir vs irse) #8

Question

I chose B. Vais. My problem is...the question never mentions a "destination." Is site wrong? or am I misunderstanding?

source: http://www.spanishdict.com/topics/practice/108

Are you going with us? - ¿___ con nosotros?

Lo siento. Incorrect. Because the action is focused on the destination, you will use the ir form for nosotros which is vais.

A. Os vais B. Vais

Answer 1

If you chose B, then you were correct. The question is talking about "going", not "leaving".

Are you going with us? - ¿Vais con nosotros?

Are you leaving with us? - ¿Os vais con nosotros?

There is also a typo in the explanation... it should say "vosotros", and not "nosotros":

Lo siento. Incorrect. Because the action is focused on the destination, you will use the ir form for vosotros which is vais.