The correct answer is D) None of the above. Considering the range of opinions on virtually every aspect of parenting, there is no commonly agreed conventional wisdom.
That is why is so difficult t come up with one aspect to be considered part of the conventional wisdom regarding proper parenting that has withstood the test of time.
It all depends on the parent's background, culture, customs, and family tradition. For one culture, conventional wisdom can be one thing, while for another culture can be completely the opposite.
The traditional way to raise children for the American family is completely different from the way Mexican families raise children. If we compare these two with the way Japanese families raise their children, is very different.
So traditions vary according to the way families have been educated in different parts of the world.