My biggest regret would be not sticking to things. Down the line you remember things you enjoyed doing and where it could have gone if you stuck to it. You can’t help but think could I have made something of myself if I had stuck to it, if I did it every day. The answer probably isn’t yes but it could be that you are closer to unimaginable goals then where you are now.
The correct answer is D. A prepositional phrase means that it starts with a preposition. And in these examples, D is the only one that starts with a preposition "on".
