The output expression of 1st multiplexer is:
$ Y=\bar A\bar BI_0+\bar A BI_1+ A\bar BI_2+ A BI_3$
$Y=\bar A\bar B.0+\bar A B.1+ A\bar B.1+ A B.0$
$Y=\bar A B+ A\bar B= A\oplus B$
The output expression of 2nd multiplexer is:
$X=\bar Y\bar CI_0+\bar Y CI_1+ Y\bar CI_2+ YCI_3$
$X=\bar Y\bar C.0+\bar Y C.1+ Y\bar C.1+ YC.0$
$X=\bar Y C+ Y\bar C$
$X=(\overline{A\oplus B}) C+ (A\oplus B)\bar C$
$X=(\bar A\bar B+AB)C+(\bar AB+A\bar B) \bar C$
$X=\bar A\bar BC+ABC+\bar AB\bar C+A\bar B\bar C$
Option $(B)$ is correct.