Could be false. Although we would be able to conclude that some people who consider work environment important also consider salary important, or that all recent grads who consider work environment important also consider salary important, we don't know about all people.

Must be true. As shown below, we can combine the claims that some recent graduates consider work environment important and that all recent graduates consider vacation policy important. We know there must be at least one recent graduate who has both of those qualities, so that implies at least some people who consider work environment important also consider vacation policy important.

Could be false. We know that some veteran employees are the only workers who consider stress level important. But we cannot infer anything else about these veteran employees. In addition, although some recent grads consider work environment important, this doesn't imply that some veteran employees do not consider work environment important.

Could be false. Although we would be able to conclude that some people who consider vacation policy important also consider salary important, or that all recent grads who consider vacation policy important also consider salary important, we don't know about all people.

Could be false. Although we would be able to conclude that some people who consider salary important do not consider stress level important, or that all recent grads who consider salary important do not consider stress level important, we don't know about all people.