Java Array Traversal Logic

The following method is intended to calculate the total price of all items in a shopping cart, which is represented by an array of Item objects.

/** Returns the total price of all items in the cart.
 *  Precondition: The cart array has been initialized.
 */
public static double totalPrice(Item[] cart) {
    /* method body */
}

Which of the following code segments, when substituted for /* method body */, will cause the method to function correctly?

I.

double total = 0;
for (int i = 0; i <= cart.length; i++)
    total += cart[i].getPrice();
return total;

II.

double total = 0;
for (Item item : cart)
    total += item.getPrice();
return total;

III.

double total = cart[0].getPrice();
for (int i = 1; i < cart.length; i++)
    total += cart[i].getPrice();
return total;