为什么派生类重载删除运算符被调用？

问：

#include <iostream>
using namespace std;
struct A 
{
    virtual ~A() {  cout << "~A ";};
    void operator delete(void* p) 
    {
        cout << "A :: operator delete" << endl;
    }
    
    void operator delete[](void* p) 
    {
        cout << "A :: operator delete[]" << endl;
    }
};
struct B : A 
{
    ~B(){ cout << "~B ";}
    void operator delete(void* p) 
    {
        cout << "B :: operator delete" << endl;
    }
    void operator delete[](void* p) 
    {
        cout << "B :: operator delete[]" << endl;
    }
};
int main() 
{
    A* ptr1 = new B;
    A* ptr2 = new B[2];
    delete ptr1;
    delete [] ptr2;
}

输出：

~B ~A B :: operator delete
~B ~A ~B ~A A :: operator delete[]

删除基类指针 ptr1 时，将调用派生类删除运算符方法，但是在删除 ptr2（保存派生类数组的动态内存位置）时，将使用基类删除运算符方法。谁能解释这种行为？