选择C
此句为虚拟句,而且是虚拟句中比较难的一项：错综虚拟
If从句中的had followed是对过去的虚拟,指的是“假如过去有遵循...”
主句的“would be”是对现在的虚拟,指的是“现在将康复了”
相同类型的句子还有：
If he had not gone out that evening,he would be alive now.
If I had taken good care of my plant,it would grow well now.