In the given network of AND and OR gates f can be written as

A

$$X_{0} X_{1} X_{2} X_{3}........X_{n}+X_{1} X_{2}+......X_{n}+ X_{2} X_{3}....X_{n}+.......+X_{n}$$

B

$$ X_{0} X_{1}+X_{2} X_{3}$$

C

$$ X_{0}+ X_{1}+X_{2} +.......+X_{n}$$

D

$$X_{0} X_{1} + X_{3}......X_{n-1}+4 X_{2} X_{3}+X_{5}+.....X_{n-1}+.......+X_{n-2}X_{n-1}+X_{n}$$