To streamline the hiring process, the human resources department decided that every applicant, regardless of their prior experience, must complete an online assessment.

The correct answer to the question "To streamline the hiring process, the human resources department decided that every applicant, regardless of their prior experience, must complete an online assessment." is Option B: applicant, regardless of his or her prior experience, must complete.

The other options — A) applicant, regardless of their prior experience, must complete, C) applicant, regardless of their prior experience, should complete, D) applicants, regardless of their prior experience, must complete — are incorrect for this GMAT Exam Prep question. As explained above: The pronoun 'their' is plural, but 'every applicant' is singular. Subject-pronoun agreement requires a singular pronoun. 'His or her' correctly refers to the singular 'every applicant', making option…