Why does this code print the correct string?

Our professor wrote this code to demonstrate scanning and printing strings,

char flower[7][50];
int i, n;
for (i = 0; i < 7; i++)
{
    printf("Enter the name of the flower number %d : ", i + 1);
    scanf("%s", &flower[i][50]);
}
printf("\nEnter the number of the flower you want : ");
scanf("%d", &n);
printf("Flower number %d is %s\n", n, flower[n]);

I have been using C for almost 2 years now, and I feel like I grasped the fundamental concepts pretty well. But, for some reason, I just can’t understand this piece of code.

Why is scanf("%s", &flower[i][50]) used here instead of scanf("%s", flower[i]) or scanf("%s", &flower[i][0])? What does that 50 even mean?
Why is the index n used rather than n - 1 in printf("Name %d is %s\n", n, flower[n])?

I did ask her about it, but the answers she gave were not very comprehensive. She said that "because we used i+1 in the loop to print 1 instead of 0, we are going to use the same index to print the string needed, hence why we use flower[n]", which doesn’t answer anything.

Any help would be appreciated. Thanks in advance!

I entered the following strings followed by the index :

Rose
Lily
Tulip
Orchid
Carnation
Hyacinth
Chrysanthemum
6

Output :

Hyacinth

>Solution :

It seems as if your professor is probably thinking that arrays index from 1 (like they maybe do in some other languages), when they actually index from zero in C.

This is evidenced by this:

printf("Enter the name of the flower number %d : ", i + 1);

And then this:

scanf("%s", &flower[i][50]);

&flower[i][50] is the same as &flower[i + 1][0].

However, that is not a valid address on the final iteration of the loop, because the actual array indexes from [0] to [6]. This will invoke Undefined Behaviour.