"All of them are good people."
Translation:Sie sind alle gute Leute.
That is an awful mistake really, they completely left out the verb in the solution, wtf.
The second one is only correct if you leave out the "sie" - "Alle sind gute Menschen."
@jaye16 : No article is used + nominative case (I think) + plural = "gute Leute" Check this link for more information on German adjectives and their inflection: https://en.wikipedia.org/wiki/German_adjectives#Weak_and_strong_inflection