Answer:
Global changes are caused mostly by humans.
Driving cars instead of walking, burning fuels for cooking and heating, manufacturing, transporting, and much more are human activates that have caused global warming/changes over time...
I am not really sure about the context of this question, but I believe the best answer would be C.
The first choice seems to symbolize elements that are not really true American heritage but rather cultural.
The second choice, I believe, pertains more towards having fun. However, one can stretch the meaning giving modern events to represent a facet of American culture (guns) but it doesn't really represent heritage.
The last choice seems to also have a playful tone regarding the Lone Ranger. In specifics, however, the Lone Ranger and Wild West is not really representative of neither the entire American culture nor American heritage.
That's why I believe choice C, or "grandmother knits the names...", is the best option to choose.
