In the following passage some of the words have been left out. Read the passage carefully and select the correct answer for the given blank out of the four alternatives.
Passage:

The generation gap is another of those characteristic features that set Homo sapiens apart from other animals. It is ______ if ever the most intelligent of apes ever blamed its juniors for their ______ ways! Over the years people have tried to analyse it, explain it, understand it, even ignore it, but it remains, ready to ______ each generation as it tries to ______ its own ______ about life and living.