In a study of intraspecific aggression (aggression directed toward other members of the same species), an experimenter finds that 16 out of 23 animals tested in species A exhibit aggression, while only 6 of 25 are aggressive in species B. Do the two species differ significantly in terms of intraspecific aggression?

a. What is the degree of freedom? _________

b. What is the chi-square value? _________

c. Do the two species differ significantly in terms of interspecific aggression? _________