The first true piece of sports equipment that man invented was t

The first true piece of sports equipment that man invented was the ball. In ancient Egypt,as everywhere,pitching stones was a favorite children's game．But a badly thrown rock could hurt a child．Looking for something less dangerous to throw,the Egyptians made what were probably the first balls. At first,balls were made of grass or leaves held together by vines．Later they were made of piece of animal skin sewed together and stuffed with feathers or hay. Even though the Egyptians were warlike,they found time for peaceful games．Before long they had developed a number of ball games,each with its own set of rules．Perhaps they played ball more for instruction than for fun．Ball playing was thought of mainly as a way to teach young men the speed and skill they would need for war. The ball was probably invented because__．
A、throwing stones often caused injuries
B、throwing stones was not fun
C、games with stones did not have rules
D、rocks were too heavy to throw
【正确答案】：A
【题目解析】：从文章中可以提取出以下关键信息来支持答案A：“But a badly thrown rock could hurt a child. Looking for something less dangerous to throw, the Egyptians made what were probably the first balls.” 这段话明确说明了埃及人发明球的原因是因为投掷石头可能会伤害孩子，他们寻找了一个不那么危险的替代品，即球。 A选项“throwing stones often caused injuries”（投掷石头经常导致伤害）直接对应了文章中提到的埃及人发明球的动机。 B选项“throwing stones was not fun”（投掷石头不好玩）在文章中并未提及，且与发明球的动机无关。 C选项“games with stones did not have rules”（用石头玩的游戏没有规则）同样在文章中并未提及，且与发明球的动机不符。 D选项“rocks were too heavy to throw”（石头太重了以至于不能投掷）虽然在某种程度上可能暗示了石头的危险性，但文章中没有直接说明这是发明球的原因。 因此，根据文章内容，最合理的答案是A，即球被发明的原因是因为投掷石头经常导致伤害。