Please can someone help me :(

The physical feature that makes up part of the border between canada and the united states is the

As you drive in to school, you hear a random radio-show caller arguing that sun exposure really has not been shown to cause skin cancer and that some research suggests that skin cancer is completely genetic and not related to sun exposure at all. at the time, you think that this is a silly argument and that the caller does not know what she is talking about. however, two months later, you are outside without wearing sunscreen, and you find yourself remembering that you had read something about how the sun actually does not cause skin cancer. this process is evidence that has influenced your attitude

"six months ago, several of molly's friends joined the trimtime fitness center. each of them participated in trimtime's weight-reduction and fitness regimen. all reported substantial weight reduction, and all are visibly slimmer. molly is convinced. she joins trimtime and enrolls in the program, hoping and expecting to see the same results. she is especially delighted to learn that trimtime had adjusted its program to make it even more effective in a shorter period of time." what is the feature in question/attribute of interest in this argument?