The correct answer is: C. employee skill category.
A skills search requires that the employee file be accessible by employee skill category because this is the most efficient way to find employees with the desired skills. By searching by skill category, you can quickly and easily identify all of the employees who have the skills you are looking for. This can save you a lot of time and effort, especially if you are looking for employees with a specific set of skills.
The other options are not as efficient for a skills search. Employee position is not as helpful because it does not necessarily indicate the skills that an employee has. Applicant file is not as helpful because it only includes information about applicants who have applied for a job, not all employees. Employee name is not as helpful because it requires you to search through all of the employee files individually, which can be time-consuming.
Therefore, the correct answer is C. employee skill category.