What Does "The Principle of the Indifference of the Indicator

What does "the principle of the indifference of the indicator" mean?

A) Highly g-loaded tests can contain any kind of content (e.g. ,verbal,numerical,spatial,etc. ) .
B) All mental ability tasks are equally good measures of g.
C) Mental ability test performance is most accurately assessed by a neutral,unbiased observer.
D) Individuals make fewer errors on mental ability tests when they are unconcerned about the task,rather than being highly anxious about it.
E) Different methods of factor analysis produce identical estimates of tests' g-loadings.