Attrition is best described as the number of:

Attrition refers to the gradual reduction of a workforce due to employees leaving the organization without being replaced. This contrasts with turnover, which includes both departures and replacements. Attrition typically results from resignations, retirements, or other natural separations.

Explanation of Other Options:

A. Employees who have resigned: Resignations are a part of attrition but do not define it entirely.

B. Employees compensated to leave the organization: This describes severance agreements, not attrition.

C. Fired employees in a given time period: Involuntary terminations are not specific to attrition.