the coefficients of x^2y^2,yzt^2 and xyzt in the expansion of (x+y+z+t)^4 are in the ratio

(a) 4:2:1 (b)1:2:4

(c)2:4:1 (d)1:4:2

Note: The said concept is beyond your grade level. However, we have provided you the suitable answer for it.”




You can also solve this question by expanding where X=x+y and Y=z+t, and expand X, Y later. But this method will be very lengthy.