What Is One of the Main Problems in Research Reporting

What is one of the main problems in research reporting that may cause readers to question the credibility of a study?

A) Research reports are too complex, making them difficult to understand and use in future research.
B) Qualitative reports fail to use the rigorous logic of quantitative research, making it difficult to replicate the findings in future research.
C) Methods and procedures are not explicitly described, making it difficult to verify or replicate the findings in future research.
D) Researchers fail to cite earlier research, making it difficult to verify their sources to aid future research.