Employers use preliminary screening interviews to

offer jobs to the best candidates.

give employment tests.

find out as much as possible about each job candidate.

narrow the field of applicants.

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Employers use preliminary screening interviews to "narrow the field of applicants".

Explanation:

A screening interview refers to a kind of job interview that is led to decide whether the candidate has the capabilities expected to carry out the responsibility for which the organization is contracting. Sometimes you are called for screening interview thus we can say that it is a first interview during the hiring process.