There are four baskets, W, X, Y and Z, each containing a particular variety of oranges. The number of oranges in any basket is unknown. The average weight of the oranges in the four baskets combined is 120 gm. The average weights of the oranges in the baskets W, X, Y and Z, individually, are 90 gm, 100 gm, 144 gm and 160 gm respectively. If the average weight of the oranges in W and X put together is 96 gm and the average weight of the oranges in X and Y put together is 120 gm, what is the ratio of the number of oranges in basket W to that in basket Z?

1) 9:1
2) 2:1
3) 4:3
4) 5:4