In His Match Against the "Cunning Opponent," Why Did Kasparov

In his match against the "cunning opponent," why did Kasparov exhibits signs of fear and confusion?​

A) ​Because he was playing against a computer that could challenge him intellectually.
B) Because he couldn't help thinking about the rapid fall of the Soviet Union.
C) ​Because he was trying to trick his opponent into thinking he had won.
D) Because,after winning five straight games,he was tired.
E) Because he saw a basic flaw in the reasoning of his opponent.