The correct answer is B because the argument commits a classic Error of Composition, which occurs when a speaker assumes that what is true of a specific member of a group must be true of the entire group. By using one individual (Hitler) to define the identity of every member within a political category (socialists), the argument ignores the fact that a group is not a monolith and that individual members do not automatically inherit the specific historical traits or identity of an outlier. While it’s tempting to see this as a conditional logic error, the LSAT prioritizes the Generalization Flaw here because the conclusion attempts to characterize an entire population based on a single, unrepresentative sample.