Immediate action was needed,the scientists decided. Give one example each of “ defensive " and “ offensive " action mentioned in the text.

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Please find below the solution to the asked query:

Defensive measure was to live in underground bunkers.
Offensive measure was a gigantic nuclear explosion suitably placed, suitably directed and suitably timed by placing a nuclear payload in a spaceship, sending it to intercept the approaching comet and detonating it by remote control.

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