单选题

页面有一个按钮button id为 button1，通过原生的js 设置背景色为红色？

Question

A. document.getElementById("button1").style.backgroundColor="red";

B. document.getElementById("button1").style.backgroundcolor = "red";

C. document.getElementById("button1").style.backGroundColor ="red";

D. document.getElementById("button1").style.bgcolor = "red";