C++: which constructors are called in vector

I have a trivial allocator:

// alloc.h
#include <cstdlib>
#include <new>
#include <iostream>

template <class T>
struct Mallocator {
  typedef T value_type;
  Mallocator() {
        std::cout << "default ctor is called" << std::endl;
  }
  template <class U> Mallocator(const Mallocator<U>&) {
        std::cout << "copy ctor is called" << std::endl;
  }
  T* allocate(std::size_t n) {
    std::cout << "Mallocator::allocate(size_t n) is called, n = " << n << " ";
    if(n > std::size_t(-1) / sizeof(T)) throw std::bad_alloc();
    if(T *p = static_cast<T*>(std::malloc(n*sizeof(T)))) {
        std::cout << "return p = " << std::hex << (uintptr_t)p << std::dec << std::endl;
        return p;
    }
    throw std::bad_alloc();
  }
  void deallocate(T* p, std::size_t n) { 
      std::cout << "Mallocator::deallocate(T *p, size_t n) is called, p = " << std::hex << (uintptr_t)p << std::dec << " n = " << n << std::endl;
      std::free(p);
  }
};
template <class T, class U>
bool operator==(const Mallocator<T>&, const Mallocator<U>&) { return true; }
template <class T, class U>
bool operator!=(const Mallocator<T>&, const Mallocator<U>&) { return false; }

And this is the client code (only one of A, B, C is used):

#include "alloc.h"
#include <vector>
#include <iostream>
using namespace std;

int main() {
    Mallocator<int> a;
    cout << "---instantiate---" << endl;
    // vector<int, Mallocator<int>> v(a);                  // A
    vector<int, Mallocator<int>> v{Mallocator<int>(a)};    // B
    // vector<int, Mallocator<int>> v(Mallocator<int>(a)); // C
    cout << "---push_back(1)---" << endl;
    v.push_back(1);
    cout << "---push_back(2)---" << endl;
    v.push_back(2);
    cout << "---push_back(3)---" << endl;
    v.push_back(3);
    cout << "---push_back(4)---" << endl;
    v.push_back(4);
    cout << "---push_back(5)---" << endl;
    v.push_back(5);
    cout << "---exiting---" << endl;
}

The output, no matter A or B is used, is always this:

default ctor is called
---instantiate---
---push_back(1)---
// omitted for brevity..

My question:

(1) if A is present, the allocator is just constructed once, that's understandable. But when B is present instead of A, apparently the copy constructor of Mallocator is called in B, but the output doesn't reflect this. Why?

(2) If B is present, which constructor of std::vector is called? In this reference, the only constructor that takes an initializer list doesn't look like this. And if I use C instead of B, it won't compile, and the error message of clang++ is not helping..

Eidt: I know this allocator is trivial but it is not the point of this question..