"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, ❤❤❤.
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