Final answer:
The sport Morgan borrowed the net from for the game was basketball. Invented by James Naismith, basketball's indoor netting was used by William G. Morgan to create volleyball.
Step-by-step explanation:
The sport that Morgan borrowed the net from for the game was basketball. The game referenced is volleyball, which was invented by William G. Morgan in 1895. Morgan sought to frame a game which will combine all elements of basketball, baseball, tennis, and handball.
Notably, basketball itself was invented just a few years earlier, in 1891, by James Naismith. Since Morgan required a net, and due to the indoor nature of basketball, it is likely that Morgan borrowed the net from the basketball courts. The establishment of basketball and volleyball both took place in the context of a growing sport culture in the United States during the late 19th and early 20th centuries, around the same time as the surge in popularity of college football.