Finding Pareto Optimality Consider an exchange economy with two individuals and 2 commodities. The endowments of the commodities are 1 each. Which one of the following are Pareto Optimum.

a. {$\frac{1}{2},\frac{1}{2},(\frac{1}{2}\frac{1}{2})$} b. {$(\frac{1}{4},\frac{1}{4}),(\frac{1}{2}\frac{1}{2})$} c. {$(\frac{3}{4},\frac{3}{4}),(\frac{1}{2},\frac{1}{2})$} d. None of the above.

I have a hunch that it is d. I am assuming that preferences are perfect complements and hence all the options from a to c will give the two individuals lesser utility. Hence d. Is this the right way to go about it. If not, please help?
To be a Pareto optimum, there must not exist another feasible allocation that makes every agent at least as well off and one or more agents strictly better off. 

So, let us consider the options here. 

Answer B - look at the individual allocations here and consider them relative to the economy's total endowment. Since the allocations given here do not exhaust the economy's total endowment, we could make one of the agents better off by simply giving him some of what has not been allocated. Doing this would not make the other agent worse off. So B cannot be P.O. 

Answer C - Consider the allocations here relative to the total endowment. Is such an allocation feasible? 

Answer A - Has the total endowment been allocated? If so, is there any way to increase what one agent has without decreasing what the other has?