Salesforce JavaScript Developer Practice Exam

The use of the splice method in JavaScript allows you to modify an array by adding or removing elements at specified positions. In this particular case, when you're looking to add 'Feb' into the array ['Jan', 'March', 'April', 'June'], you would typically invoke the splice method by specifying the index where you want to insert 'Feb'.

If you use the following code:

```javascript

let months = ['Jan', 'March', 'April', 'June'];

months.splice(1, 0, 'Feb');

```

Here, the first argument of splice (1) indicates the index at which to start modifying the array (between 'Jan' and 'March'), the second argument (0) specifies that no elements should be removed, and the third argument ('Feb') is the element to be added. As a result, 'Feb' will be inserted at index 1, pushing 'March', 'April', and 'June' to the right.

Thus, the resulting array after this operation will be ['Jan', 'Feb', 'March', 'April', 'June']. This outcome corresponds perfectly with the choice provided, making it the correct answer. The order of the elements is preserved, and 'Feb' is added