Paleoclimatologists study ice cores to investigate Earth’s past climate. They use methods such as oxygen isotope analysis. Which feature inside the ice are the scientists interested in analyzing and why?

Letter a, because when there are unlike charges they will always attract to each other.

If the heat engine is a perfect carnot cycle engine, thenefficiency = (t2-t1)/t2   where t1=temperature of cold reservoir ( ° k) = 135            t2=temperature of hot reservoir ( ° k)   = 325thereforeefficiency = (t2-t1)/t2 = (325-135)/325 = 0.5846 = 58%  note: this is the theoretical maximum efficiency of a perfect heat engine.   real-life engines do not achieve this value.