Which statement is true of primary sources? A. They are often full of strange details and unrealistic settings.
B. They may use words that are unfamiliar now but were common long ago.
C. They interpret data collected in surveys, presenting a conclusion.
D. They are written by experts who’ve conducted research on a time period.

B. They may use words that are unfamiliar now but were common long ago.

An example of a primary source is a diary. The diary allows us to see into the thought process of a certain individual at that given time period. Because language changes over time, it's likely they'll use words that aren't that common or perhaps not even used anymore. The general rule is that the further back you go, the past language is less connected with the present language.