The correct answer and the word that best describes the tone of this excerpt from John Steinbeck's "The Grapes of Wrath" (1939) is A. Disgusted.
This excerpt belongs to chapter 5 of "The Grapes of Wrath", in which banks and landowners decide to evict farmers from their lands because they cannot make high profits from that farming model. The sentence "times are changed" points to this fact. Tractors arrive to the farmlands to evict the farmers and plow the land, razing the farmhouse if necessary. The farmers protested against it and against the people driving the tractors, usually their own neighbors. The driver is disgusted with the situation because they are also facing problems and cannot think about other families. Their own families are starving and the bank pays three dollars a day for this job, so while they are disgusted, they have to take care of their own kids.