**Core Concept**
High cereal intake and poor nutritional balance can lead to an imbalance of essential amino acids, particularly in individuals relying heavily on plant-based protein sources. Cereals are often low in the essential amino acid lysine and high in methionine, leading to a potential deficiency.

**Why the Correct Answer is Right**
The correct answer is related to the concept of limiting amino acids in plant-based diets. Lysine is an essential amino acid that is commonly limiting in cereal-based diets. When individuals consume high amounts of cereals and have poor nutritional balance, they may develop a deficiency in lysine, leading to various health complications.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is incorrect because it is not directly related to the high cereal intake and poor nutritional balance scenario. While it may be a deficiency in certain situations, it is not the most likely outcome in this specific context.
**Option B:** This option is incorrect because it is not a direct consequence of high cereal intake and poor nutritional balance. Although it may be related to certain dietary deficiencies, it is not the most relevant answer in this scenario.
**Option C:** This option is incorrect because it is not a common deficiency associated with high cereal intake and poor nutritional balance. While it may be a concern in certain situations, it is not the most likely outcome in this specific context.

**Clinical Pearl / High-Yield Fact**
In plant-based diets, it is essential to consume a variety of foods to ensure adequate intake of all essential amino acids. This can be achieved by combining cereals with legumes, nuts, or seeds to create a complete protein source.

**Correct Answer:** C. Lysine.