What conclusion can we reach about environmental hindrances to mental ability, such as poor prenatal care, exposure to toxins, or stressful family circumstances?

a. Lack of environmental nutrients can lead to IQ score gaps of many points when comparing children raised in deprived environments to those who are not,

b. Environmental hindrances affect intellectual development between the ages of birth and 5 years, but after that deprived children rebound quickly and resume normal intellectual functioning.

c. The presence of even a single environmental hazard will decrease IQ scores by 12 points.

d. Environmental hindrances have less of an impact on children with strong inherited mental agility, compared to children with weaker genetic material.