What is the result of executing this program code?

Consider the following program code:
1.$x = 100;
2.$y = “-25”;
3.$sum = $x + $y;
4.
5.print $sum;
What is the result of executing this program code?

A.
The code will output the following:
100-25

B.
The code will output the following:
75

C.
The code will fail at line 3 because $y contains string data.

D.
The code will output the following:
125