Explanation
Buck's feet, unlike the compact and hard feet of the huskies, had grown softer over the long years since his kind was first tamed by cave-dwellers or river men. Throughout the day, he walked with visible discomfort and, once camp was set up, he would collapse from exhaustion. Despite his hunger, he remained still, prompting François to hand-feed him.
Choice B is the best answer. The text mentions that Buck's feet are softer, which causes him discomfort and leads to exhaustion.
Choice A: The text makes no reference to Buck's age.
Choice C: The text does not indicate that it is the harsh climate that causes Buck discomfort; rather, it points to his softer feet as the cause.
Choice D: Although the text mentions that François feeds Buck by hand, it does not say that Buck can eat on his own.
✨ Expert's Tip ✨
Find the key parts in the text that describe Buck's condition and its cause.