In the given network of AND and OR gates f can be written as:
a) X0 X1 X2 .....Xn + X1 X2 . ....Xn + X2 X3 ....Xn.... Xn
b) X0 X1 + X2 + X3 +....... +Xn-1 . Xn
C) X0+X1+ X2+ .......+ Xn
d) X0 X1 X3........ Xn-1 + X2+X3+X5 ......... Xn-1 + ........+ Xn-2 + Xn-1 +Xn