how is phoebe more realistic of the two?

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this does not help me.

So it doesn't! Sorry about that. Phoebe does not share her brother's views. Where Holden is sentimental, Phoebe is realistic. She realizes how angry her father will be at Holden and refuses to listen to Holden when he tells how he will go to a ranch in Colorado. Like Carl Luce, Phoebe confronts Holden with his own immaturity and lack of direction, but this criticism goes farther. Even a nine year old child can realize that Holden needs to mature, yet Holden has not come to this revelation himself.

thanks so much!

Glad to help.