Yep. I agree what the first person said. The most reliable and trustworthy sites out of all these are .gov and .edu. From these two if you're talking about school work research then you should go with .edu.
The add level Adds another row to the dialog box so additional columns can be sorted while the delete level removes any unwanted level. How to access it: Press the down arrow beside the sort order tab. Tap the button "The Largest to Smallest". Tap the Add level button.
For the best-case: Because there is a chance that you take two gloves of the same color in the first two round the answer is two.
For the worst-case: The worst case would be if, for each color-group of gloves you take the right or left glove, for example, you take 5 left-hand red gloves then 4 left-hand yellow gloves, then 2 left-hand green gloves, because you have already taken all of the left gloves the next one is going to be a right glove that is going to pair with one of the already selected gloves, therefore, the answer is 12 -> 5+4+2+1 = 12
