Final answer:
Option d. 'Zoos had long been one of the most serious offenders.' is a minor supporting detail about the rescue and relief of chimpanzees.
Step-by-step explanation:
The sentence from the passage 'Chimps and Us' that is a minor supporting detail about the rescue and relief of chimpanzees is option d. 'Zoos had long been one of the most serious offenders.' This sentence implies that zoos have been involved in activities that have been harmful to chimpanzees, which would require rescue and relief efforts.