Answer:
The belief that prevents Gideon from sharing his people's knowledge with the Farquars is:
(b)He thinks white people are only interested in making money for themselves by exploitation.
Step-by-step explanation:
The Farquars are a family living in South Africa and Gideon is their native cook in Doris Lessing's short story "No Witchcraft for Sale". Gideon uses his knowledge of healing plants to prevent Teddy Farquar from getting blind after a snake spit in his eyes. However, when a scientist comes to their home and asks to be shown the miraculous plant, Gideon feels betrayed by the family.
He does not understand the family does not care about the possible money to be made from this. In truth, when they are told about the money by the scientist, the Farquars are annoyed. All they wanted was to help others the way Gideon helped their son. But, to Gideon, white people only care about money, selling what has been passed on from generation to generation. There is prejudice from both sides: The Farquars see Gideon as their inferior and are unable to understand his stubbornness; Gideon sees white people as greedy beings who only care about exploiting others.
In the end, he does not reveal which plant it is that did the trick. Still, he and the family go back to their original relationship, caring about and respecting one another.