Scientists were unsure about the last common ancestor between apes and humans because fossils are so scarce, researchers do not know what the last common ancestors of living apes and humans looked like or where they originated.
In the options given below the isomer given in the option A of 1-tert-butyl-5-methylcyclohexane is the most stable of all. The IUPAC name for this compound is 1-tert-butyl-3-ethyl-5-methylbenzene.
