Read this phrase: "the dogs began to salivate at the sound of the laboratory assistants' footsteps." What does the apostrophe after "assistants" show?

1. An apostrophe placed after the final s of a plural word marks ownership by that whole plural group. 2. "Assistants" names more than one assistant, and the footsteps are theirs. 3. So the apostrophe shows the footsteps belong to more than one assistant, option B. 4. Option A is the trap: one assistant would be written "assistant's," with the apostrophe before the s. 5. No letters are missing, so this is not a shortened form like "don't," ruling out option C. _Source: OpenStax Psychology 1e (CC BY 4.0), Ch 6 "Learning", section 6.2 Classical Conditioning_