According to von Thünen's model, rural land values and land use is shaped by
population density.
distance from the city.
the type of economic system that develops.
Crop yields.
migration patterns.

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.

Answer metamorphic rock;

When the indian plate collided with eurasian plate because it was cool 

Ithink its b but i'm not sure.