Answer:Two
Explanation:
You should place at least 2 obstacle between yourself and pursuer in order to prevent yourself in case the dangerous person attacks you.
Obstacles can play important role by playing a role of shield between you and the pursuer and buys you time to escape from his vision or reach.
While you are trying to get out of trauma that you are being attacked someone obstacles create a hindrance to pursuer to give you time to think rationally.