3.设置按钮背景色自上向下渐变，从顶部白色渐变到底部银色，下列写法正确的是（ ）。
A.background-image: linear-gradient(to bottom, #f0f0f0 0%, #e0e0e0 100%);
B.background-image: linear-gradient(to bottom, 0% #f0f0f0, 100% #e0e0e0);
C.background-image: linear-gradient(to bottom, 0%, #f0f0f0, 100%, #e0e0e0);
D.background-image: linear-gradient(to bottom, #f0f0f0, 0%, #e0e0e0, 100%);