The liver is the organ that is involved in degradation of toxins (which you may have inferred from the fact that when individuals drink lots of alcohol, they claim to be giving their liver a “hard time”). Thus, based on this, you know that whatever organelle is responsible for degradation of toxins is likely to be over expressed in liver cells.  The nucleus is responsible for holding the DNA and also producing rRNAs (from the nucleolus), but this is not relevant to degradation, which makes A incorrect. The lysosome tends to be involved in autophagy and degradation of internal cell waste, which is not related to detoxification (which is relevant to external waste). The mitochondria is the powerhouse of the cell and produces ATP, but also has nothing to do with degradation of toxins, which makes it incorrect. And lastly, the rough ER is involved in the production of proteins that, via the endomembrane system, end up being a part of the cell membrane. This function can be inferred by the presence of ribosomes on the rough ER that give it its name. Since this also has nothing to do with degradation, it is also incorrect. 

Thus, by the process of elimination, the correct answer is D. The Smooth ER is responsible for various functions, including removal of toxins and lipid biosynthesis. Thus, places like the ovaries and testes, which secrete lots of steroid hormones (which are a subclass of lipids) also have large Smooth ERs.