Final answer:
Acheulean tools are best described as hand-axes made by careful chipping of stones, which are part of the Acheulean industry associated with Homo erectus and early Homo sapiens.
Step-by-step explanation:
The question relates to Acheulean tools, which is a term that refers to a specific type of prehistoric stone tool technology. The correct answer to the question 'Which phrase best describes Acheulean tools?' is a. hand-axes made by careful chipping of stones. Acheulean tools, characteristic of the Acheulean industry, were created by Homo erectus and early Homo sapiens and are known for their distinctive teardrop shapes and bifacially flaked edges. These tools represent an advanced form of early human technology and provide insights into the manual dexterity and cognitive abilities of our ancestors.