You and some friends disagree as to whether a particular fellow student could be described as selfish. To settle this argument, it is decided that you will all observe her behaviour. What conditions would be necessary in order to come to a valid conclusion?​

answer; collective security;

i only have part a but here is the first one: - lewis and clark are born

- lewis marries sacajawea and clark is jealous  

- clark drowns lewis and then goes to jail

answer; /// decreasing responsiveness to a stimulus to which one is repeatedly exposed;

answer' recieve unequal treatment as a group;