Concept:The correct word must mean to commit a harmful or illegal act.
Explanation:The underlined word "penetrate" means to go into or through something.
This does not fit the context of "such a mindless act on his friends."
Now examine the options:
"Perpetuate" means to make something continue indefinitely.
"Perpetrate" means to carry out or commit a harmful, illegal, or immoral action.
"Precipitate" means to cause something to happen suddenly or prematurely.
Only "perpetrate" accurately describes committing a mindless act.
Therefore, it is the best substitution.
No improvement is not needed because the original word is incorrect.
Answer:Option B: perpetrate