已知a=list(range(10)),执行以下指令后，a的值会变成?
a[:2]=[5]
a.pop(5)
a.remove(5)
[2, 3, 4, 5, 7, 8, 9]
[2, 3, 4, 7, 8, 9]
[2, 3, 4, 6, 7, 8, 9]
