The sex ratio tends to be low where women have:

A) greater access to health care than do men.
B) about equal access to medicine men do.
C) less adequate nutrition than men do.
D) All of the above.
E) None of the above.

The sex ratio tends to be low where women have less adequate nutrition than men do. This is because female fetuses tend to be more vulnerable to malnutrition in utero, leading to higher rates of miscarriage and lower births of females. Additionally, in societies where women have less access to resources, families may selectively abort female fetuses or practice female infanticide, further lowering the sex ratio. Greater access to health care or equal access to medicine would not necessarily have an impact on sex ratio, as these factors do not directly affect differential treatment or access to resources based on gender.