画布是canvas，如何获取该画布的画笔？

画布是canvas，如何获取该画布的画笔？
A.varctx=canvas.getContext('4d');
B.varctx=canvas.getContext('1d');
C.varctx=canvas.getContext('3d');=
D.varctx=canvas.getContext('2d');
正确答案：D