Final answer:
a) Love. According to Polonius in Hamlet by Shakespeare, the force that causes the most insanity and self-destruction in the world is love.
Step-by-step explanation:
According to Polonius in the play Hamlet by William Shakespeare, the force that causes the most insanity and self-destruction in the world is love. In Act 1, Scene 3, Polonius advises his son Laertes about the dangers of love, saying '...the borrowed majesty of love, which the false man does easy. In the cap of youth there is something of the lover, the youth is often slain with lover’s eyes' (I.iii.158-161). Polonius suggests that love can lead people to act irrationally and make destructive decisions.