Question

which things you think of that is only one of its kind​

Answer 1

Answer:

The correct construction is: the only one of its kind

In this sentence “kind” is a class of things, e.g., cars, animals, etc.

So let’s say you have a rare automobile…perhaps a Packard Panther. Only four were ever built and two remain. You have “one of the last of its kind.” If the other one is destroyed, now you have “the only one of it’s kind.”

Similarly, if a species of animal was becoming extinct the last one would be “the only one if its kind” left on earth.

If you make “kind” plural, then you’re trying to say the thing or creature under discussion is the only one left in more than one classification. While that may be possible, you would need to phrase it differently, e.g., the thing in question is the only one of its kind in more than one category: category a, category b, and category c.

Hope it will help you!