Why Is Advisable to Avoid Consent as a Legal Basis

Why is advisable to avoid consent as a legal basis for an employer to process employee data?

A) Employee data can only be processed if there is an approval from the data protection officer.
B) Consent may not be valid if the employee feels compelled to provide it.
C) An employer might have difficulty obtaining consent from every employee.
D) Data protection laws do not apply to processing of employee data.