Given these code segments:

struct vehicle

$\{$

int year;

float mileage;

$\}$;

vehicle a;

vehicle b;

What is the output of the following code segment?

a$.$year $=2015$;

a$.$mileage $=50000\mathrm{.}0$;

b $=$ a;

cout $<<$ b$.$year $<<$ endl;

Question $3$ options:

$2015$

Syntax error.

$201550000$