Sentence A — "Everyday social life is impossible without interpersonal relationships." — This is a broad sociological statement, presented as a truth about society, so it is treated as a Fact (F).
Sentence B — "The root of many misunderstandings has been cited in poor relations among individuals." — This is evaluative and analytical, so it is a Judgement (J).
Sentence C — "Assuming the above to be true, social life will be much better if people understand the importance of good interpersonal relations." — This is a conclusion drawn from A and B, hence an Inference (I).
Sentence D — "A study reveals that interpersonal relations and hence life in general can be improved with a little effort on the part of individuals." — This is based on research findings and is verifiable, hence a Fact (F).
Thus, the classification is: F (A), J (B), I (C), F (D) → FJIJ.