Final answer:
The distinctive fluted spear points used by early Native Americans to hunt Ice Age mammals were d. Clovis points, essential for their survival during the Paleo-Indian period.
Step-by-step explanation:
Early Native Americans used Clovis points to hunt large-bodied Ice Age mammals. These distinctive fluted spear points were part of the Clovis culture's toolkit, which also included hand axes and implements made of bone. Clovis points, dating back between 11,000 and 13,000 years, were attached to shafts to serve as spears or darts and were essential for hunting megafauna like mammoths and mastodons.
The development of the Clovis point signifies an important period known as the Paleo-Indian era, during which humans employed tools such as the atlatl to increase the range and speed of their spears. This era reflects the innovative adaptability of early humans in the Americas as they spread throughout the Western hemisphere, hunting and gathering for survival.