why does the given code show segmentation fault

#include <stdio.h>
int abs(int a)
{
    if(a>0)
        return a;
    else
        return -a;
}
int max(int a,int b)
{
    if(a<b)
        return b;
    else
        return a;
}
int closest(int* arr,int n,int x)
{   int min=arr[0];
    int diff=abs(arr[0]-x);
    for(int i=1;i<n;i++)
    {
        if(abs(x-arr[i])<diff)
           {
             min=arr[i];
             diff=abs(x-arr[i]);
           }
        else if(abs(x-arr[i])==diff && min!=arr[i])
        {
            min=max(min,arr[i]);

        }
    }
return min;
}
int main()
{
int testCases;
//printf("enter the number of test cases \n");
scanf("%d",&testCases);
int arr[testCases][100];
for(int i=0;i<testCases;i++)
{
  //printf("enter the number of elements in the array and the test element \n");
    int n,k;
    scanf("%d %d",&n,&k);

    //printf("enter the array \n");
    for(int j=0;j<n;j++)
    {
      scanf("%d",&arr[i][j]);
    }
    printf("%d\n",closest(arr[i],n,k));
}
}

why does this show segmentation fault?