Evidence of climate changes and conditions that affected early societies are gathered from , written records, ice core samples, tree rings, maps

Very early societies did not have a written language or even ways to efficienly preserve information, so we can reject the options "maps" and "written records".

As far as the other two options go - ice core samples and tree rings, both are correct! probably "ice core" samples are the better answer, since only fossilized tree rings would tell us about the very early societies.