Two Individuals $\mathrm { A }$ And $\mathrm { B }$ , Consume Two Goods

Two individuals, $\mathrm { A }$ and $\mathrm { B }$ , consume two goods, $x$ and $y$ . Together they have 4 units of $x$ and 8 units of $y$ . For Consumer $\mathrm { A }$ the $M R S _ { x , y } ^ { A } = \frac { 5 x } { 3 y }$ and for Consumer $\mathrm { B }$ the $M R S _ { x , y } ^ { B } = \frac { 3 x } { y }$ . Which of the following allocations is an efficient allocation of goods $x$ and $y$ ?

A) Consumer A has 5 units of $x$ and 3 units of $y$ , and Consumer B has 3 units of $x$ and 1 unit of $y$ .
B) Consumer A has 3 units of $x$ and 5 units of $y$ , and Consumer B has 1 unit of $x$ and 3 units of $y$ .
C) Consumer A has 2 units of $x$ and 6 units of $y$ , and Consumer B has 6 units of $x$ and 2 units of $y$ .
D) Consumer A has 7 units of $x$ and 2 units of $y$ , and Consumer B has 1 unit of $x$ and 6 units of $y$ .