The childhood level living scale was questioned as to its validity because

It's because there were reservation about the scale's sensitivity to cultural diversity.
In different culture, the expectation that both parents and the kids's peers tend to be really different.
This would very much influence the children's interest which would defintiel influence their living scael.

The correct answer is a. when they started making tools that will them in cultivating lands, they could raise crops and that made them attached to one place for a longer period of time. after that, they started domesticating animals and building their own permanent settlements that resemble the ones we have today.