Answer:
b. Antarctica's ice
Step-by-step explanation:
Earth is flatter at the South Pole than the North Pole because of the weight of the Antarctica's ice.
The Antarctica ice cap is the largest single mass of ice on earth. It covers almost 14 million square kilometers and it weighs 26,500,000 Gigatons.
As a result of this heavy weight, it compresses the South Pole of the earth causing the earth to be flatter at the South Pole.
This gives the Earth its slight pear shape.