Which of the following aspects of data collection ensures definitions are clear and procedures are uniform?

The correct choice is C because a systematic approach refers to a structured and organized methodology for collecting data. By employing a systematic approach, researchers can establish clear definitions for their variables and ensure that their procedures are consistent across all cases in a study. This uniformity is crucial in research, as it helps maintain the integrity of the data and allows for reliable comparisons and conclusions.

A systematic approach typically involves following a predetermined set of protocols, which aids in minimizing biases and inconsistencies that could arise from personal interpretations or variations in procedure. This approach leads to replicable results, which is a fundamental aspect of scientific research.

On the other hand, subjectivity introduces personal bias and interpretation, which can cloud the clarity of definitions and lead to inconsistent procedures. Empirical evidence pertains to the data or observations that researchers gather, but does not specifically address the clarity of definitions or uniformity of procedures. Randomness, while valuable in certain experimental designs, relates more to the selection of participants or conditions rather than ensuring clarity in data collection methods.