在如下源代码文件 Test.java 中 , 哪个是正确的类定义?
A.
public class test {public int x = 0;public test(int x) {this.x = x;}}
B.
public class Test{public int x=0;public Test(int x) {this.x = x;}}
C.
public class Test extends T1, T2 {public int x = 0;public Test (int x) {this.x = x;}}
D.
protected class Test extends T2{public int x=0;public Test(int x){this.x=x;}}