Final answer:
The case that prevented employment discrimination against women with preschool-aged children while allowing men with such children to be hired is Phillips v Martin Marietta Corp. Option B is correct.
Step-by-step explanation:
The 1971 U.S. case that stated an employer may not refuse to hire women with preschool-aged children while hiring men with such children, in the absence of a business necessity, is Phillips v Martin Marietta Corp. This landmark decision helped to shape the application of Title VII of the Civil Rights Act of 1964, which makes it unlawful for employers to discriminate based on sex, among other protected characteristics.
The case of Phillips v Martin Marietta Corp. advanced the interpretation that sex-based discrimination in employment practices is prohibited unless there is a Bona Fide Occupational Qualification (BFOQ) justifying the discrimination.