What will be the output of the following C++ code?

#include <iostream>
using namespace std;
class Box
{   
    double length;
    double breadth;
    double height;
    public:
    double getVolume(void)
    {  
        return length * breadth * height;
    }
    void setLength( double len )
    {   
        length = len;
    }
    void setBreadth( double bre )
    {   
        breadth = bre;
    }
    void setHeight( double hei )
    {   
        height = hei;
    }
    Box operator+(const Box& b)
    {  
        Box box;
        box.length = this->length + b.length;
        box.breadth = this->breadth + b.breadth;
        box.height = this->height + b.height;
        return box;
    } 
};
int main( )
{  
    Box Box1;
    Box Box2;
    Box Box3;
    double volume = 0.0;
    Box1.setLength(6.0);
    Box1.setBreadth(7.0);
    Box1.setHeight(5.0);
    Box2.setLength(12.0);
    Box2.setBreadth(13.0);
    Box2.setHeight(10.0);
    volume = Box1.getVolume();
    cout << "Volume of Box1 : " << volume <<endl;
    volume = Box2.getVolume();
    cout << "Volume of Box2 : " << volume <<endl;
    Box3 = Box1 + Box2;
    volume = Box3.getVolume();
    cout << "Volume of Box3 : " << volume <<endl;
    return 0;
}

A. Volume of Box1 : 210
Volume of Box2 : 1560
Volume of Box3 : 5400

B. Volume of Box1 : 200
Volume of Box2 : 1560
Volume of Box3 : 5400

C. Volume of Box1 : 210
Volume of Box2 : 1550
Volume of Box3 : 5400

D. Volume of Box1 : 200
Volume of Box2 : 1000
Volume of Box3 : 5260

Answer: Option A