Which of the following represents the best definition of I.Q.in childhood?

A) A measure of how well a child performs a task compared to other children
B) A genetically determined predictor of academic success
C) A fixed quantity of inborn intelligence
D) An environmentally determined predictor of academic success

I.Q. in childhood is a measure of a child's cognitive ability and how well they perform tasks compared to other children of the same age group. It is not a fixed quantity or a genetically determined predictor of academic success, but rather a dynamic measure that can change over time with exposure to different experiences and learning opportunities.