Why did vassals have to serve lords?

Because the lords gave them their land in return if someone attack the land the vassals would protect it they got land for protecting and then if they got a big enough land they could sell some and become lords and then they would have vassals so you could get land and then sell some of it and you would get vassals

Explanation: I have taken the test before and I know because I like this kind of stuff. :)

the three roles stated in the dialogue develop the siblings' personalities.

lloyd's personality looks like a trademarketer

dana's personality is afraid from lloyd's behavior and the oldest sister is a decided person who tries to solve any conflict

the answer is