Inactive Tutor answered 10/16/20
What an interesting question!!
The main issue is to look at the welfare values of the possible allocations. The key allocations are Y with equal allocation to both agents, and Z which has massively more total utility than any other choice.
The three questions choose an allocation based on different methods of assessing welfare.
(a)
A Pareto Optimal allocation is when no agent can be better off, without making at least one other agent worse off. With Y and Z together (answer B) the total allocation is {267, 33}. Changing from this allocation to any other option will make either type-1 or type-2 agents (or both) worse off.
(b)
A Rawlsian Welfare Function measures the society welfare by the worst-off member. It requires maximization of the worst case.
X, W, Z all have agents with only 11 utils. Hence Y is better as no agent has less than 22 utils. However, X and W together (answer C) would give a minimum welfare of 33 utils per agent!
(c)
A utilitarian measure society welfare based on the total welfare (regardless of inequality). Z (answer B) has a total of 256 utils, far more than the other options.