设变量已正确定义,选项( )与以下程序段不等价。 switch(op){ case '+': printf("%d", value1 + value2); default: printf("Error"); case '-': printf("%d", value1 - value2); } A. if(op == '+'){ printf("%d", value1 + value2); printf("Error"); }else if(op != '-'){ printf("Error"); } printf("%d", value1 - value2); B. if(op == '+'){ printf("%d", value1 + value2); printf("Error"); printf("%d", value1 - value2); }else if(op == '-'){ printf("%d", value1 - value2); }else { printf("Error"); printf("%d", value1 - value2); } C. if(op == '+'){ printf("%d", value1 + value2); }else if(op == '-'){ printf("%d", value1 - value2); }else { printf("Error"); } D. switch(op){ case '+': printf("%d", value1 + value2); case '-': printf("%d", value1 - value2); default: printf("Error"); }