下列行为构成家庭暴力的是（）。

A.李某无业，打麻将上瘾，家有一子（3周岁）无人看管，在打麻将时为防止孩子跑掉，用铁链将其拴住

B.张某失业在家，心情不好，经常酒后把老婆捆在凳子上不让其睡觉

C.老孙的儿媳泼辣，经常谩骂老孙

D.小学生小花经常被继母恐吓要把她卖到外地

In June of 1973, nine whales beached on the Florida coast. Beaching means swimming out of the ocean onto the beach, and usually dying there. No one knows why they do it, but a number of whales beach themselves every year. Some people think beaching is an accident.
Perhaps the whales get confused. Scientists who studied the beaching of three dozen whales in Australia think the whales may have been confused by loud noises, Whales can tell where they are by sounds. They send out sounds and listen as they travel past or bounce off objects. Two days before these thirty-six whales beached, loud guns had been fired for two hours. The loud sounds may have confused the whales. Their confusion might have caused them to wander into low water.
Whatever the reason whales beach, it is a sad event. People try to save them, but very few beached whales live. One whale that was rescued from beaching in Florida lived for forty-five days. That is the longest a beached whale has ever survived. And it lived that long only because it got attention from doctors.
All over the world, scientists rush to whale beachings as soon as they hear about them. They hope to learn why whales beach, and how to save them.

One reason whales beach may be ______.

A．because they are hungry

B．because they are attacked

C．that people can study them

D．that they are confused