选择正确的 .melt() 参数

给您一张名为 inflation 的表。请选择能得到与下表相同输出的选项。

   country    indicator  year  annual
0   Brazil  Inflation %  2017    3.45
1   Canada  Inflation %  2017    1.60
2   France  Inflation %  2017    1.03
3    India  Inflation %  2017    2.49
4   Brazil  Inflation %  2018    3.66
5   Canada  Inflation %  2018    2.27
6   France  Inflation %  2018    1.85
7    India  Inflation %  2018    4.86
8   Brazil  Inflation %  2019    3.73
9   Canada  Inflation %  2019    1.95
10  France  Inflation %  2019    1.11
11   India  Inflation %  2019    7.66