Students Conducted a Research Project in Which They Hypothesized That

Students conducted a research project in which they hypothesized that women,more than men,would stop studying and look at each person who enters a library study room.Results indicated that women did make more head movements than men when people entered the library.To be confident about these results,we would want to make sure their results are not affected by

A) unobtrusive measures.
B) desensitization.
C) demand characteristics.
D) expectancy effects.