Judge by Judge on This is a confusing thing

How is the correct way to write the question?

Question
When you visit a host family that wants to take a kid in, what do you judge whether they are elidgbile to take in the kid on, room space, how nice the couple is?

When you visit a host family that wants to take a kid in, what do you base whether they are elidgbile to take in the kid on, room space, how nice the couple is?

When you visit a host family that wants to take a kid in, how do you base whether they are elidgbile to take in the kid on, room space, how nice the couple is?

What do you judge the family on?
What do you judge the family by?

What are the different criteria for choosing a host family?

Answer
We judge whether a family is elidgible to take a child in on how big their house is, whether the couple gets along well and how enthusiastic they are to have an exchange student for a year.

We base whether a family is elidgible to take a child in on how big their house is, whether the couple gets along well and how enthusiastic they are to have an exchange student for a year.

Thank you for your time