It's called the Social Security Trust Fund, and it's typically taken directly from wages. If you ever get a job, on your pay stub there will be a deduction that's usually just called "SOCIAL SECURITY". So, largely payroll taxes.
C is correct answer.
Tonga is an archipelago of high/and low islands.
Hope it helped you.
-Charlie
Its due to erosion. Erosion slowly breaks down everything down, that why we have places like The Grand Canyon.