Which of the Following Accurately Describes 18O/16O Ratios of Ice

Which of the following accurately describes 18O/16O ratios of ice sheets?

A) The higher the ratio of oceanic 18O to 16O,the cooler the temperature is because 18O will be locked up in ice sheets.
B) A higher ratio of oceanic 18O to 16O indicates a warmer period during which more 18O evaporates and precipitates onto ice sheets.
C) During periods of colder temperatures,the 18O/16O ratio is higher because only the 18O isotope is being evaporated.
D) During warmer periods,16O evaporates more readily and,therefore,the 18O/16O ratio is significantly lower than cooler periods.
E) During cooler periods,18O evaporates more readily and,therefore,the amount of 16O in glaciers is negligible.