Final answer:
Alfred Binet and Louis Terman were central figures in the development of intelligence testing, with David Wechsler further advancing the field with his scales. Seguin, although impactful in the education of individuals with disabilities, did not directly contribute to the development of psychometric tests such as the IQ test.
Step-by-step explanation:
History of Psychometric Testing
The history of psychometric testing is rich and significant in the field of psychology, particularly pertaining to the measurement of intelligence. Alfred Binet played a pivotal role in this history by being tasked by the French government to develop an intelligence test to identify children who may face difficulties in school. His work led to the Binet-Simon Intelligence Scale, which was later standardized and normed by Louis Terman, becoming a precursor to the IQ tests commonly used in educational settings today. The most widely used IQ tests in the present day are the Wechsler scales, developed by David Wechsler, who introduced the Wechsler Adult Intelligence Scale (WAIS) amongst others.
As for the role of Seguin in 1866, while he was a significant figure in the history of education and care for individuals with disabilities, his work is not directly associated with the creation or development of psychometric tests like the IQ test. Therefore, choices a, b, c, and d in the original question do not accurately describe Seguin's contribution in the context of psychometric testing.