Calculate the Rsam, i.e the ration of ¹⁸O:¹⁶, in the following substances.

a. Snow falling in Antarctica at a temperature of -35 degree Celsius.

b. Calcite from a benthic (i.e. bottom dwelling) foraminifera growing during the Oligocene on the polar North Atlantic.

c. Calcite from a planktonic (i.e. surface dwelling) foraminifera growing in today's central North Pacific at 15 degree Celsius.