I think it's A but here's an explanation anyway: as you heat the crude oil, the different hydrocarbons, having different boiling points, boil and evaporate up the column. Those with lower boiling points, shorter in chain length, will condense nearer the top of the fractional distillation column. Those that are more viscous, larger in chain size, will have high boiling points, so will evaporate last and condense lower down in the column. Therefore, you achieve all the different oils / materials (oil, petrol, gasoline, tar etc etc). I hope this helps. If not, then a good website to use is 'BBC bitesize, fractional distillation'.
Fractional distillation of crude oil. Because they have different boiling points, the substances in crude oil can be separated using fractional distillation. The crude oil is evaporated and its vapours allowed to condense at different temperatures in the fractionating column.
young - earth geologists believe that sedimentry rocks form during the flood. classic sedimentry rocks likely began as particles of eroded rock, which were transported and deposited in a different location, compacted, and finally cemented in place
