Fill in the blank with the correct preposition.
Bin Laden has lived __________ the gun all his life

by

The correct preposition to fill in the blank is by. The preposition by is used to indicate means or agency. In this case, Bin Laden has lived by the gun all his life, which means that he has made his living through violence.

The other options are incorrect.

• For is used to indicate purpose or destination.
• On is used to indicate location or position.
• Through is used to indicate movement or passage through something.