that 通常指代 前文提到的同一事物,如
The population in China is much larger than that in Japan.
that 与 population 指的是同一事物.
而这道题中 现在的marketing strategy 与过去的不同(differ),因此不能用 that.
可以说marketing strategy differs greatly from the one in the past.
D选项也是对的.