题目

    We know that hugs make us feel cosy inside. And this feeling could actually ward off stress and protect the immune (免疫) system, according to a new research from Carnegie Mellon University. It’s a well-known fact that stress can weaken the immune system. In this study, the researchers sought to determine whether hugs could protect individuals from the increased sensitivity to illness brought on by the particular stress that comes with interpersonal conflict. “We know that people experiencing ongoing conflicts with others are less able to fight off cold viruses. We also k 由x＞y，得出ax≥ay的条件是 [　　] A．a＞0 B．a＜0 C．a≥0 D．a≤0