The correct option is
A Endomitosis and endopolyploidy
Tapetum is the innermost layer of anther wall. It is single layered and the cells have dense cytoplasm and prominent nuclei. A very common feature of the Tapetum is that total DNA content increases enormously in the meiotic prophase. This may arise due to many reasons one of which is endomitosis. Endomitosis is also known as Endopolyploidy. It is a type of mitosis in which there is chromosome duplication and the chromatids separation take place within the intact nuclear membrane because there is no spindle formation. This results in large polyploid nucleus.
So, the correct answer is D.