Step 1: Think about the timeline:
Let us place the four names on a rough timeline. Binet and Simon made their scale around 1905. Stern proposed the IQ ratio in 1912. Wechsler built his scales from 1939 onwards.
Galton studied individual differences earlier, but in a different way.
Step 2: Decide what the question asks:
The question asks who was one of the first to work on intelligence as a measurable ability of children. The school based testing tradition begins with Binet.
Step 3: Why Binet fits:
Binet was asked by the French government to find children who would not gain from normal classes. His test measured judgement, memory and reasoning. The textbook therefore names him as an early worker on intelligence.
Step 4: Why Wechsler does not fit:
Wechsler designed tests for adults and children after the Binet tradition had already begun. He is a later figure, so option 2 is wrong.
Step 5: Why Galton is not the expected answer:
Galton measured things like reaction time and sensory skill. His work was not an intelligence test in the Binet sense and the standard textbook answer here is Binet. So option 3 is not chosen.
Step 6: Why Stern does not fit:
Stern gave the IQ formula using Binet's mental age. His work came after Binet's, so option 4 is wrong.
Step 7: Conclude:
Binet matches the question, so the answer is option 1.
Final Answer:
Alfred Binet is the answer.
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