Read the passage. These trains were not toys, and they were detailed models, and they were built to try out ideas. For real trains.
What is the best way to combine these incorrect sentences into one complete sentence?

a. These trains were not toys. They were detailed models. They were built to try out ideas. The ideas were for real trains.
b. These trains were not toys, they were detailed models, they were built to try out ideas for real trains.
c. These trains were toys and detailed models, and they were built to try out ideas for real trains.
d. These trains were not toys; they were detailed models built to try out ideas for real trains.

Which sentences from part 1 of the call of the wild would best serve as evidence of the theme "sometimes survival depends on knowing when not to fight"? buck had accepted the rope with quiet dignity. to be sure, it was an unwonted performance: but he had learned to trust in men he knew, and to give them credit for a wisdom that outreached his own. he had merely intimated his displeasure, in his pride believing that to intimate was to command. but to his surprise the rope tightened around his neck, shutting off his breath. he saw, once for all, that he stood no chance against a man with a club. he had learned the lesson, and in all his after life he never forgot it. that had given them an unfair advantage; but now that it was off, he would show them. they would never get another rope around his neck.