Analyzing Array Traversal Code

An integer array nums has been declared and initialized with one or more values. Which of the following code segments correctly counts the number of negative values in nums and stores the result in the counter variable?

I.

int counter = 0;
int i = -1;
while (i <= nums.length - 2)
{
    i++;
    if (nums[i] < 0)
    {
        counter++;
    }
}

II.

int counter = 0;
for (int i = 1; i < nums.length; i++)
{
    if (nums[i] < 0)
    {
        counter++;
    }
}

III.

int counter = 0;
for (int i : nums)
{
    if (nums[i] < 0)
    {
        counter++;
    }
}