Answer:
Stone.
Step-by-step explanation:
The root word in the given word "eolithic", that is italicized is "lith" is a combining form meaning "stone" and given birth to different variants like megalith, batholith, acrolith, angiolith, etc. The word 'eolithic' comprises of two words the suffix "eo-" meaning 'early' and the root word "lith" meaning in a linking form "stone". The other options are irrelevant to the context of the meaning of the word. Thus, the third one is the answer.