**Overview:**
The stem of a plant plays a crucial role in supporting and transporting nutrients throughout the plant. While some plants can be grown from stem cuttings, others cannot. In this case, the correct answer is option D - Potato. Let's explore why.

**Explanation:**

**1. Carrot:**
Carrots cannot be grown from the stem of a plant. Carrots are root vegetables, which means they are grown from the taproot, not the stem.

**2. Radish:**
Similar to carrots, radishes are root vegetables and cannot be grown from the stem of a plant. They are cultivated from the swollen taproot.

**3. Turnip:**
Turnips are also root vegetables and cannot be grown from the stem of a plant. The edible part of the turnip is the swollen taproot.

**4. Potato:**
Potatoes can be grown from the stem of a plant. In fact, potatoes are typically grown from pieces of the stem known as "seed potatoes." These seed potatoes are small pieces of mature potato tubers that contain buds called "eyes." When planted in soil, the eyes sprout and produce new stems and roots, eventually forming a new potato plant.

**5. None of these:**
This option is incorrect because, as explained above, potatoes can indeed be grown from the stem of a plant. Therefore, the correct answer is not "None of these."

In conclusion, out of the given options, only potatoes can be grown from the stem of a plant. Carrots, radishes, and turnips are root vegetables and are grown from the taproot, not the stem.

Carrot