The correct answer is D) Terman's longitudinal study of over 1500 gifted children.
Beliefs that being gifted or a genius lead to being weird, socially awkward, or more likely to suffer from mental illnesses were put to rest by Terman's longitudinal study of over 1500 gifted children.
Joel N. Shurkin published the study called "Terman's Kids. The Ground Breaking Study of How the Gifted Grow Up." Professor Lewis Terman (1877-1956) was an American psychologist that developed the Stanford-Binet intelligence test. As a Stanford professor, he published the work "The Measurement of Intelligence" in 1916. In 1921 he did research on gifted children. He picked 158 students from the state of California that had IQ's exceeding 140. He found that these children tended to have better health and stability that the rest of children.