The correct answer is - c. Paleo-Indians relied less on hunting big animals and more on fishing and gathering food.
Once the Ice Age ended, the landscape in North America changed significantly, the ice sheets melted and this allowed lots of rivers and lakes to emerge, as well as the plants to flourish in much of the continent and cover the parts that were once covered with ice. The new lakes and rivers allowed the Paleo-Indians from the interior of the continent to rely more on fishing and have fish as daily diet. The fruit trees, berries, root vegetables, that spread in most of what is now the territory of USA provided the Paleo-Indians with huge amounts of seasonal food. This two new food providers enabled the Indians to be more reliant on the nature as a food source and to not risk their lives on a daily basis while hunting some of the megafauna that roamed the North American continent.