**Core Concept**
Trans fatty acids (TFAs) are a type of unsaturated fatty acid with at least one double bond in a trans configuration, differing from the more common cis configuration. TFAs are created during the hydrogenation process of vegetable oils, which increases their shelf life and stability. However, this process alters the fatty acid structure, making TFAs more saturated and less beneficial for cardiovascular health.

**Why the Correct Answer is Right**
The primary concern with TFAs is their adverse effect on cardiovascular health. TFAs increase the levels of low-density lipoprotein (LDL) cholesterol, commonly known as "bad" cholesterol, while decreasing high-density lipoprotein (HDL) cholesterol, or "good" cholesterol. This imbalance increases the risk of heart disease and stroke. TFAs also affect the function of endothelial cells, leading to impaired vasodilation and inflammation.

**Why Each Wrong Option is Incorrect**
* **Option A:**
* **Option B:**
* **Option C:**
* **Option D:**

**Clinical Pearl / High-Yield Fact**
It's essential to note that TFAs are not only found in processed foods but also in some cooking oils, such as partially hydrogenated soybean and canola oil. The American Heart Association recommends limiting daily intake of TFAs to less than 1% of total daily calories.

**Correct Answer: A. All of the above**