PLZ HELP M If polar ice falls into the ocean, which two spheres are interacting?

A the hydrosphere and the geosphere
B the atmosphere and the biosphere
C the hydrosphere and cryosphere
D the geosphere and the atmosphere

Ascientist is designing an investigation to study the impact of invasive bird populations on local, native bird populations at backyard bird feeders. what population is most likely to be a control group for the investigation? amount of food number of bird feeders invasive bird populations local backyard birdfeeders without food