A 2016 column in the New York Times notes that: “about two decades ago … employers began replacing traditional [pension] plans with ‘defined contribution’ plans like 401(k)’s.”

a. What are “traditional pension plans,” and how do they differ from 401(k) plans?
b. Briefly explain why 401(k) plans might be more desirable to employers and employees than traditional pension plans. Are there any reasons why 401(k) plans might be less desirable to either group?