What is the significance of the cup of coffee billy has when he camps at bluebird creek with his father and grandpa in the book where the red fern grows asap

the subject is reading but it's not on their sorry?

How did the discovery of the rhesus factor affect society? o more patients died from having a transfusion with the wrong rhesus factor 0 new treatments during pregnancy could prevent harm to the developing child. o less donated blood could be used in the treatment of patients. the number of blood types was reduced by half