Please help with:

struct studentType1{

string name;

int ID;

float gpa;};

struct studentType2{

string name;

int ID;

float gpa;

};

studentType1 student1, student2;

studentType2 student3, student4;

Which of the following statements is valid c++:

1.student2.ID = ID;

2.student2 = student3;

3.student1=student4;

4.student1.ID=student3.ID

Thanks