Remark
There fewer people who see it the better if you are still a little uncertain about what to say or how to say it.
A
Given the remark, I think this is the place to start. Mothers are especially tolerant about listening to a first time speech. The criticism is very light. You will benefit most by hearing what it sounds like. I would pick A as the answer.
B
You have an awful lot of nerve if you are going to talk in front of an audience that large with an unprepared speech. Good luck.
C
At a science fair is not a bad choice. The groups are small, and you will get to explain your project many times before you see a judge. That will give you the necessary experience to polish what you have to say.
D
How do you feel about talking in front of classmates with a teacher giving you a mark? Not the best place to start.
Conclusion. Please Read
Where you start depends on what you are talking about. The science fair option is a good one if that is your intended audience. For all other assignments, I'd pick A. If this is a question that actually came from a physics class then pick C.
