What will be the time complexity of given code?

#include <bits/stdc++.h> 
using namespace std;  
void convert(int a[], int n) 
{ 	
	vector <pair<int, int> > vec; 	
	for (int i = 0; i < n; i++) 
		vec.push_back(make_pair(a[i], i)); 	
	sort(vec.begin(), vec.end()); 	
	for (int i=0; i<n; i++) 
		a[vec[i].second] = i; 
} 
void printArr(int a[], int n) 
{ 
	for (int i=0; i<n; i++) 
		cout << a[i] << " "; 
} 
int main() 
{ 
	int arr[] = {10,8,2,5,7}; 
	int n = sizeof(arr)/sizeof(arr[0]); 	
	convert(arr , n); 
   	printArr(arr, n); 
	return 0; 
}

A. O(n)

B. O(n log n)

C. O(n²)

D. O(log n)

Answer: Option B