Everything can be evaluated and measured by objective and subjective measurements. In doing so, the objective and subjective validity varies, depending on which measurements we have applied, objectively or subjectively. Thus there are two objective criteria - production quantity and production quality, and there are two subjective critera - supervisor and self-ratings. Objective validity is applied when impartial measurement is to be performed without prejudice and bias, that is, when it is simply necessary to estimate the result based on the effect of some product. Subjective validity is applied when someone's performance, style and quality of performance should be measured, when the assessment is done based on scoring of a performance, such as gymnastics or sporting competition.
Both objective and subjective validity are not always applicable, and their importance depends on the purpose and therefore their significance differs from the events to the events.
The answer is: b.