$29.$ Hawkeye, Klinger, and O'Reilly Builders is a large corporation with a number of subsidiaries, including plumbing, drywall installation, electrical, and roofing companies. Given the large number of subsidiaries, which endorsement should the corporation make sure is added to its workers compensation policy to ensure automatic coverage for all subsidiaries?

$($Search Chapter $3)$

a$.$ broad form named insured endorsement

b$.$ broad form additional insured endorsement

c$.$ additional insured endorsement

d$.$ miscellaneous insureds endorsement