A) Sometimes, when a worker gets more education, it allows her or him to help coworkers increase their productivity on the job. This is an example of an externality. Describe conditions under which the presence of this kind of externality increases the socially efficient level of education subsidies. Describe conditions under which presence of this kind of externality does not increase the socially efficient level of education subsidies. Explain.

B) Why is the current structure of benefits and funding for U.S. Social Security expected to be unsustainable without a change in the Social Security law? Give a complete set of reasons as you can.