What will be the time complexity of the following code?

#include <bits/stdc++.h> 
using namespace std; 
 
void func(int a[], int n, int k) 
{ 
	if (k <= n) 
	{ 
		for (int i = 0; i < k/2; i++) 
		swap(a[i], a[k-i-1]); 
	} 
 
} 
int main() 
{ 
	int a[] = {1, 2, 3, 4, 5}; 
	int n = sizeof(a) / sizeof(int), k = 3; 
	func(a, n, k); 
	for (int i = 0; i < n; ++i) 
		cout << a[i]<<" ";
	return 0; 
}

A. O(k)

B. O(n)

C. O(k log k)

D. O(n log n)

Answer: Option A