The earliest (that is, the oldest) stone tools are referred to as:

a. Oldowan

b. Acheulean

c. Mousterian

d. Hominid

The correct option is : a. Oldowan

Explanation:

The Oldowan or Mode I tools are the simply earliest or the oldest recognizable tools, preserved in the archaeological records.

The oldest Oldowan tool is dated about 2.6 million years ago and was found in Gona, Ethiopia. These tools were used in the Lower Paleolithic period, about 2.6 million years ago until 1.7 million years ago. These tools were used in Africa, Middle East, South Asia and Europe, by the early humans.