Pundits and commentators often state (correctly) that entitlement spending (spending on Medicare, Medicaid, and Social Security) is

Question:

Pundits and commentators often state (correctly) that entitlement spending (spending on Medicare, Medicaid, and Social Security) is going to explode in the future. But by lumping all three together, we obscure the source of the explosion.
a. Which of the three really won’t be “exploding” all that much compared with the other two?
b. Which category of federal spending is projected to actually decline in future decades?