Please choose the correct answer to the question: Which of the following is a crucial piece of evidence supporting scientists' theory of how the continents and the ocean basins formed?

Answer1: Gravitational forces result in the fusion of small atoms. Answer2: A differentiated iron core expresses magnetic properties. Answer3: Currents redistribute heat in an unevenly heated liquid. Answer4: A stream of charged ions disperses lightweight gases.

Answer format: answer1/answer2/answer3/answer4