According to Thurston, the primary factor in intelligence is :
A. Spatial Ability
B. Associative Memory
C. Problem Solving
D. Perceptual Speed
E. Reasoning
Choose the correct answer from the options given below :

Correct option is D

The correct answer is (d) E Only.
L.L. Thurstone proposed a theory of intelligence that diverged from the idea of a single, unified intelligence factor, which was prominently advocated by Charles Spearman through his "g" factor theory. Thurstone suggested that intelligence consists of several primary mental abilities rather than a single general intelligence factor. Among these primary mental abilities, Thurstone identified spatial ability, perceptual speed, number facility, verbal meaning, memory, word fluency, and reasoning.
Among the options provided, Reasoning is a primary factor in Thurstone's model of intelligence. He did not elevate one of these abilities above the others as the "primary" factor in intelligence in the sense that Spearman did with the "g" factor. However, if we interpret "primary" as referring to one of the main abilities identified by Thurstone, then Reasoning fits as a correct answer within the context of the options given. Thurstone's theory emphasizes that these different abilities operate independently and can vary independently from one person to another.