**Hint for process of elimination:** The largest part of the student body population consists of girls. Therefore, the population of girls is greater than $latex \dfrac{1}{3} $, or 33.3%, of the total population. This at least eliminating choice A. But the ratio of girls to girls plus boys is $latex \dfrac{150\%}{150\%+100\%}=3/5$, or 60%. Therefore the population of girls is under 60%. That at least eliminates both D and E. Answer C is too nice for this particular complex situation, and is also meant to draw your eye since the number $Latex 50\% $ appears twice in the problem, so I lean towards B.

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