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

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

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