Lateral surface area of a cone

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I don't have the foggiest clue how to answer this question. Also, I don't have any intuition how to answer this without memorizing formulas. I've googled and found the formula for a lateral surface area of a cone:

Now my test taking skills, I figured I can eliminate choices till I get a 50-50 guess. - My thought process knows there is 360 deg in a circle. There are nine - 40deg's in a circle. So that leaves me with B or D.
- This thought process may be wrong: (And if I was in the test without the formulas in front of me). I know that a cone and a sphere both are curved. I know the surface area of a sphere has a radius squared. So I would presume I would square the 8" to get 64. So I would choose D, here.

But as I said earlier, I do not have any intuition on how to definitively answer this question. So how about it? Am I on the right track?