Answer: a.

Explanation:
Commentate is a word and — much as I would like to — I can’t make it go away. However, let’s limit it to those uses where it might mean something slightly different from comment. According to the Random House Dictionary, commentate has been used since the eighteenth century as a synonym for annotate and since the middle of the 19th century to mean provide commentary, as a back formation from commentator.

They do, however, comment that commentate is considered jargon. Hear, hear!

So we’ve got:

Comment, meaning say something about something. And then, somewhere along the line, someone decided that a person who comments is a commentator. And THEN someone got the bright idea that what a commentator does is commentate. Apparently they didn’t realize there was a perfectly good word for that already.

I blame sports. All those commentators, commentating away about players giving 110 percent and so on.

What next? Commentation? Yes. Apparently that’s a word too. But that doesn’t mean we have to use it.

Let’s keep things simple, shall we? You’re 100 percent correct with the simplest forms of words. And there’s really no reason to aim for percentages over 100.

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