What method of manufacturing, introduced in the early 1900s, made mass production possible?

With an american government question

Nita is the office manager at a service station. two applicants, max and tim, arrive to interview for the open mechanic's position. max's clothes are dirty, his hair is unwashed, and he doesn't make eye contact when he gives nita his name. tim dresses in clean jeans and a nice shirt, is shaved, and shakes nita's hand when he introduces himself. after the interview, keith the head mechanic, asks nita what she thought. both men have the skill set needed for the position. nita recommends tim. she is responding to her perception of

Are people more motivated to change from positive or negative experiences, like slavery, womens rights, and any other historical movements/moments? i need more factual information than opinions.