单选题 某开发者想测试一下@Preview作用的组件,编写了如下代码,以下哪一项是在组件模式预览的内容? @Entry @Component struct index { @State message: string = 'Hello World' build() { Row() { Column() { test1() test2() Text(this.message) .fontSize(50) .fontWeight(FontWeight.Bold) } .width('100%') } .height('100%') } } @Preview @Component struct test1{ build(){ Text("你好HarmonyOS") .fontColor(Color.Blue) .fontSize(30) } } @Component struct test2{ build(){ Text("开始学习吧") .fontColor(Color.Red) .fontSize(30) } }