3. Two graduate students are engaged to one another, and both are working on their PhD disstertations - Riley in political science and Skylar in economics. Because both have incomes that are tied to their academic achievement, and because they plan to marry and share household income, each wants the other to complete their disstertation. However, Riley is having a motivational crisis and doesn't want to. Let the payoffs in the table represent income in thousands of dollars and, thereby, if you sum the two payoffs by cell it gives total household income. a. How do the payoffs in the table reflect Riley's motivational crisis of not wanting to complete the dissertation? Explain. b. What is the Nash equilibrium in this game? Is this the best outcome for the couple, why or why not? c. Skylar would like Riley to complete the dissertation and tells Riley, "If you don't complete your dissertation, then I' m not going to complete mine." Explain, using the numbers from the payoff matrix, why this threat is not immediately credible. d. Suppose that Riley believes Skylar's threat. Explain, referring to the payoffs in the table above, why this threat should be sufficient to motivate Riley to complete the dissertation