Please choose the correct answer to the question: The concept of continental drift, continents drifting over the ocean floors, was proposed by Alfred Wegner in 1915. This concept was replaced by the theory of plate tectonics in the 1960s. Changes from the continental drift concept to the plate tectonics theory required which of the following?

Answer1: strong earthquakes occurring along fault zones Answer2: data and ideas being shared among scientists Answer3: a scientific law being passed by Congress Answer4: teachers beginning to teach the newer theory

Answer format: answer1/answer2/answer3/answer4