Answer:
The Word "fluid " should be replaced with "Crystallised".
Explanation:
General intelligence is subdivided into Fluid intelligence and crystallized intelligence
Fluid intelligence is the ability to resolve and solve novel reasoning problems and it is correlated with a number of important skills such as comprehension, problem solving, and learning.
While Crystallized intelligence is the ability to deduce secondary relational abstractions by applying primary relational abstractions to each other.
But Note that the deduced relations among relations must be checked by fluid intelligence.
This theory was published in 1963 by the psychologist Raymond Cattell.
Also note that Fluid intelligence depends on working memory capacity, that is located in the prefrontal cortex. This region degenerates faster than other cortical regions in the course of aging and encephalopathies.
Fluid intelligence is at its peak at around age 20, and then gradually declines.
Replacing the word "fluid" with the word "crystallized " will make the statement in the question text correct.