$15.$ What will be the output printed in line #$11$ in program below?

#include $$iostream$>$

using namespace std;

int main$)$

int x;

x $=18\mathrm{.}0/4$;

cout $<<$ x $<$ endl;

retura. $4\mathrm{.}5$

b$.4$

$.0$

d$.$ unknownn