Journalist: Many people working on difficult problems in mathematics report going to sleep without a solution, but upon awaking discover they have a solution in mind. This phenomenon occurs among all age groups past infancy. Which one of the following is most strongly supported by the journalist's statements? ['Certain types of mathematical problems cannot be solved while one is consciously seeking a solution.', 'The ability to carry out mental processing gradually develops during infancy.', "Everyone's mind works unconsciously on difficult problems while sleeping.", 'Consciously seeking a solution is not the only mental process by which one can solve a mathematical problem.']