A) Reduced disease transmission rates.
B) Reduced predation risk.
C) Enhanced resource defense.
D) Decreased costs of thermoregulation.
E) Reduced search time for food.

A) They found a positive correlation between group size and the density of food trees.
B) They observed a decline in group size with a natural decline in food availability.
C) They observed an increase in group size with the experimental addition of food.
D) They observed an increase in fitness of individuals with a decline in group size.
E) They observed an increase in group size with an experimental reduction in competitors.

A) Females spend more time in habitats that harbor diseases.
B) Males have a superior immune system.
C) Females have lower levels of genetic variation.
D) Females are larger than males.
E) Females associate in tighter schools.