Could be either one. I intentionally planted some in my garden because of the story behind Queen Ann's Lace, which is another name for wild carrot. Legend has it that Queen Ann was stitching up the lace of her dress when she pricked herself with a needle and bled on the white fabric. The flower of daucus carota is a cluster of tiny white blossoms that somewhat resemble lace when viewed from above. In this flower cluster there is one red flower, symbolizing Queen Ann's blood.
However, I have seen it growing wild on several occasions and in many states. Bird droppings carry the seed and the rhizome (is a carrot a rhizome? Tuber, I think.) naturalizes and spreads.
Another fun fact, it takes two years after starting from seed to flower. I give my dogs frozen carrots in the Summer as a treat. After two years waiting for this plant to flower, I was excited. It had just blossomed when my dogs dug it up and ate the carrot. -.- That's okay though, that was years ago and they don't dig up my gardens anymore. Plus I have a nice patch of them in the back yard and I get to see that mythical flower every year.