2. why is each greasers reasoning for fighting invalid?

Brief Explanations:

Without context about who the Greasers are and their specific reasons for fighting, it's hard to determine invalidity. However, common reasons for fighting like pride, revenge, or territory - if not based on just or moral grounds - can be considered invalid. In many cases, fighting as a first - resort solution instead of communication is also invalid.

Answer:

Insufficient context to determine specific invalid reasons for each Greaser's fighting. Need more details about their reasons.