Which is more optimum using an multidimensional array like. int arr[100][100]; or pointer to pointer like int **arr; with molloc

Question

With
arr=(int**) malloc(100*sizeof(int*));
for(int i=0; i<100;i++)
arr[i]=(int*)malloc(100*sizeof(int));

Answer 1

int arr[100][100]; is allocation in stack.

int** arr = (int**)malloc( 100 * sizeof( int ) ); is allocation in heap.

How can we compare these two memory allocation method?

And what is actually meant by "more optimum"? in what way?