Dr Smith Wants to Study Temperament Differences Associated with Gender

Dr Smith wants to study temperament differences associated with gender. What problem will Dr Smith face in her research?

A) Temperament is stable and changes little over time.
B) Temperament is heritable and determined by the parents, not their offspring.
C) Caregivers respond differently to boys and girls from birth, confounding experiential with genetic influences.
D) So far, no gender differences in temperament are known to exist.