Consider the following code snippet in C language that computes the number of nodes in a non-empty singly linked list pointed to by the pointer variable head.struct node{ int elt; struct node *next; }; int getListSize (struct node *head) { if( E1 ) return 1; return E2; }Which one of the following options gives the correct replacements for the expressions E1 and E2?

We are given that the singly linked list is non-empty ($n \ge 1$).

1. Base Case (E1): If the list has only one node, then head->next == NULL. The function should return 1 in this case. Therefore, E1 must be head->next == NULL.

2. Recursive Step (E2): If the list has more than one node, the total number of nodes is $1$ (for the current node) plus the number of nodes in the remaining list starting from head->next. Therefore, E2 must be 1 + getListSize(head->next).

### Why other options are incorrect:

• Option A: Uses head instead of head->next in E2, causing infinite recursion.

• Option C: If E1 is head == NULL and returns 1, a single-node list would evaluate to 1 + getListSize(NULL) = 1 + 1 = 2, which is incorrect.

• Option D: Passes head recursively in E2, leading to infinite recursion.

Thus, B is the correct option.