While Studying Rates of Language Acquisition for New Canadians from Different

Multiple Choice

While studying rates of language acquisition for new Canadians from different countries,Curtis Cunning's research assistants informed him that 7 of the 65 subjects had quit and walked out before the study was completed.What type of threat to internal validity does Curtis' experiment have?

A) Selection bias
B) History effect
C) Experimental mortality
D) Maturation
E) Testing effect