P: Prediction, the hallmark of natural science, seems to be made possible by reducing phenomena to mathematical expressions. P: Some social scientists want to be able to predict like natural scientists, so they assume they should follow the same process of reducing phenomena to mathematical expression. C: "But this would be a mistake." P: It would be a mistake because it would neglect data that is not easily mathematized resulting in distortion.
So, the main conclusion of this argument is the sentence in which the author expresses an opinion - that it would be a mistake for social scientists to reduce phenomena to mathematical formulas. Answer choice (D) "Phenomena in the social sciences should not be reduced to mathematical formulas" is a clear restatement of this, and is therefore correct.
Answer choice (A) states: "The social sciences do not have as much predictive power as the natural sciences." This can be a tricky answer choice because it is likely true. However, it is ultimately incorrect because there is no place in the passage where this is clearly stated and it is broader than the conclusion we noted. Again, the passage's conclusion is that social scientists would be making a mistake if they reduced phenomena to mathematical formulas. (A) strays from statement too much to be correct.
Does that make sense? Please let us know if you have any other questions!