Which of the following methods is the most effective for picking the pivot element?first elementlast elementmedian-of-three partitioningrandom element

The most effective method for picking the pivot element in quicksort is the median-of-three partitioning. This method involves taking the first, middle, and last elements of the array, and choosing the median value. This approach reduces the chance of worst-case scenario and improves the efficiency of the quicksort algorithm.

Here are the steps:

1. Select the first, middle, and last elements from the array.
2. Determine which of these three elements is the median (the value that falls between the other two).
3. Use this median value as the pivot for the quicksort algorithm.

This method is generally more effective than using the first element, last element, or a random element as the pivot, as it helps to avoid the problem of choosing a 'bad' pivot that could lead to inefficient performance.