Question #N1169

The director of the museum, a passionate advocate for the preservation of endangered languages, spoke to a group of students and scholars about the importance of documenting the languages that are slowly disappearing from the world. "To understand a culture," she explained, "you need to know the language that its people speak."

Which choice best combines the sentences at the underlined portion to create a grammatically correct and stylistically effective sentence?
A. you need to know the language its people speak.
B. you need to know the language that its people speak.
C. you need to know the language its people spoke.
D. you need to know the language, that its people speak.