If the average (arithmetic mean) of x and y is positive, this means the sum of x and y is positive.

(1) The average (arithmetic mean) of x and y is 8, this gives x+y =16. but we can have (x,y) = (10,6) or (-2,18). Hence x can be negative or positive, So, it is insufficient.

(2) 2x > 2y . this gives x>y or x-y >0

and also from question stem, x+y = positive .

this gives x +y>0

Adding x-y >0 & x +y>0 , we get x>0. It is sufficient.

Answer is B.

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