Ascientist has chosen to study the motion of clouds in the atmosphere during a thunderstorm. which type of model is most appropriate for her investigation? a. computer simulation b. equation c. map d. graph

This is sort of more of an opinionated question I feel, but the answer I would go with would be A. Computer Simulation. 
Reasons: B. Equation would maybe help her calculate the rate (speed) at which the clouds are moving, but it does not actually show her the motion of the clouds, which is what she wants to study.
C. Map would allow her a visual representation of countries, not a visual representation of clouds in a thunderstorm.
D. Graph, again, would show her a visual of the rates (speeds) of the clouds moving, but she would not be able to see the actual motion of the clouds.
I say A because it allows her to see a visual diagram of the clouds moving, which she can then track how fast, how often, etc. the clouds are moving in the thunderstorm. 

This is all you, but i can give you some topics that you could try. if it rained when you want to do something outdoors, it 'limits' that human activity. maybe you want to do an experiment that goes throughout the whole year and you have to have above freezing the entire year. this 'limits' your activity. i thought of those just off of the top of my head. something that gets to me that might be getting to you is you are thinking too hard about what to do. think simply, and if it is too simple, then bump it up just a little bit.