Final answer:
Under the Drug-Free Workplace Act of 1988, a (D) technician in a company regulated by the Nuclear Regulatory Commission is subject to mandatory drug testing due to the nature of their safety-sensitive work.
Step-by-step explanation:
Under the Drug-Free Workplace Act of 1988, certain employees are subject to drug tests to ensure a safe and drug-free environment. Of the jobs listed, a technician in a company regulated by the Nuclear Regulatory Commission is most likely to be subjected to drug tests. This is because positions related to nuclear energy often involve safety-sensitive tasks where impairment could have serious consequences.
Private school teachers, retail store cashiers, taxi drivers, and software designers at companies like Microsoft unless otherwise stipulated by the specific company policies, are not specifically mandated by the Drug-Free Workplace Act to undergo drug testing.