**Core Concept**
The question is testing the difference between skeletal muscle and smooth muscle, which are two types of striated and non-striated muscles found in the human body. Skeletal muscle is attached to bones and is responsible for voluntary movements, whereas smooth muscle is found in the walls of hollow organs and blood vessels, and is responsible for involuntary movements.

**Why the Correct Answer is Right**
Smooth muscle is characterized by its ability to contract and relax without being under voluntary control, and its role in maintaining the tone of blood vessels and the motility of the gastrointestinal tract. Unlike skeletal muscle, smooth muscle lacks striations and is unable to generate rapid, forceful contractions. This is due to the absence of T-tubules and the presence of gap junctions, which allow for synchronized contraction of smooth muscle cells.

**Why Each Wrong Option is Incorrect**
* **Option A:** This option is incorrect because it does not specify a distinguishing feature between skeletal and smooth muscle. While both types of muscle can be found in the gastrointestinal tract, this is not a unique characteristic of smooth muscle.
* **Option B:** This option is incorrect because striations are actually a characteristic of skeletal muscle, not smooth muscle. Skeletal muscle is striated due to the presence of T-tubules and the organization of its contractile units.
* **Option D:** This option is incorrect because the presence of myosin light chains is a characteristic of both skeletal and smooth muscle. While smooth muscle myosin light chains may have different isoforms, this is not a distinguishing feature between the two types of muscle.

**Clinical Pearl / High-Yield Fact**
It's essential to remember that smooth muscle is not striated, and its ability to contract and relax is controlled by the autonomic nervous system. This is in contrast to skeletal muscle, which is striated and under voluntary control.

**Correct Answer:** B. Striated muscle is a characteristic of skeletal muscle, not smooth muscle.