Francois fastened upon him an arrangement of straps and buckles. It was a harness, such as he had seen the grooms put on the horses at home. And as he had seen horses work, so he was set to work, hauling Francois on a sled to the forest that fringed the valley, and returning with a load of firewood. Though his dignity was sorely hurt by thus being made a draught animal, he was too wise to rebel. He buckled down with a will and did his best, though it was all new and strange. —The Call of the Wild,
Jack London

Which sentence best supports the prediction that Buck will continue to fight against being a sled dog?

“His dignity was sorely hurt by thus being made a draught animal.”
“And as he had seen horses work, so he was set to work.”
“Francois fastened upon him an arrangement of straps and buckles.”
“He buckled down with a will and did his best.”