How does the detective hercule poirot refer to his brain agatha christie mystery novel?

Poirot the famous detective of Agatha christie mystery novel used to search the clues of any criminal case based on his extensive knowledge of human nature and human psychology. The author claims that Mr. Poirot being a deep  observant of the people's behavior and thus was able to combine the orders  to get clue to the evidences. He considers himself to be the most intellectual of all the minds in Europe and would phrase out the incidents in order to solve the case though the clue based on the physical evidences .

the correct answer is 2 and 4

maybe because its impossible for balloons to lift a whole entire house.