Option B is the correct answer because “ratiocination “ means to form judgements by a process of logic; reason, which means that it is exact and methodical thinking, hence it is correct.
Option A is incorrect because “non sequitur” means a conclusion or statement that does not logically follow from the previous argument or statement, which is not the same as methodical thinking, hence it is incorrect.
Option C is incorrect because “rationalism” means the practice or principle of basing opinions, which is not the same as methodical thinking, hence incorrect.
Option D is incorrect because “psychiatry” is the study and treatment of mental illness or emotional disturbances, hence it is incorrect.