Who was most enthusiastic about relying on eugenics for the improvement of human intellectual functioning?

The answer is: Lewis Terman

Throughout his career, Lewis Therman was obsessed in figuring out the test that can be used to separate the people with high intelligence and those with average intelligence. He also obsessed in figuring out ways for people with average intelligence could improve their intelligence.

In the end, he could only managed to developed tests to measure intellectual functioning, but never really able to find a way to improve it. He developed 9 categories of tests to measure human's intelligence, which are:L

1. Tests for creative imagination,

2. logical processes,

3. mathematical ability,

4. language mastery,

5. Interpretation of fables,

6. game of chess,

7. Memory tests,

8. motor skill.