Final answer:
Alfred Binet believed intelligence was a collection of mental abilities and developed the early intelligence test, while David Wechsler created the most widely used IQ tests today, the WAIS and WISC. The correct option is C.
Step-by-step explanation:
The psychologist who believed that intelligence was a collection of mental abilities was Alfred Binet.
Binet, working in the early 1900s, was asked by the French government to develop an intelligence test for children, which later became known as the Binet-Simon Intelligence Scale.
American psychologist Louis Terman later adapted Binet's work at Stanford University, resulting in the development of the Stanford-Binet Intelligence Scales, a normed and standardized test.
Regarding who developed the IQ test most widely used today, the correct answer is David Wechsler.
Wechsler developed the Wechsler Adult Intelligence Scale (WAIS) and the Wechsler Intelligence Scale for Children (WISC), which are both widely used modern intelligence tests. The correct option is C.