I'm not sure why this is verschiedener and not verschiedenen. Can anyone help me out?
Because it's genitive.
Ok, so couldn't one also say "Im Dienst von verschiedenen Herren"?
Yes, that works. But genitive is generally considered to be better style.
Ok, thanks. I understand that genitive is considered more elegant, but I'm not sure if the other option should be marked incorrect if it's entered.
Why "In dem Dienst verschiedener Herren" cannot pass? I thought "Im" is abbreviation of "In dem"...
Because in German you have to use 'Im' instead of 'In dem', it is not optional.