**Core Concept**
Nutritional support through Total Parenteral Nutrition (TPN) is expected to result in weight gain due to the provision of adequate calories and essential nutrients to meet the body's energy requirements. This concept is based on the fundamental principle of nutrition, where adequate caloric intake leads to positive energy balance, resulting in weight gain.

**Why the Correct Answer is Right**
TPN is administered to provide the necessary macronutrients, including carbohydrates, proteins, and fats, which are essential for energy production and tissue growth. When the body receives sufficient calories and nutrients through TPN, it utilizes this energy to support various bodily functions, leading to weight gain. The increase in weight is a result of the deposition of fat and muscle mass, which is a direct consequence of the body's energy surplus.

**Why Each Wrong Option is Incorrect**
**Option A:**
This option is not a direct consequence of TPN administration and does not accurately describe the expected outcome of nutritional support.

**Option B:**
This option is incorrect as it does not directly relate to the expected outcome of TPN. While fluid overload can occur with TPN, it is not the primary reason for weight gain.

**Option C:**
This option is incorrect as it does not accurately describe the expected outcome of TPN. While some patients may experience fluid retention, it is not the primary reason for weight gain.

**Clinical Pearl / High-Yield Fact**
A key consideration when administering TPN is to ensure that the caloric intake is adequate to meet the patient's energy requirements, as inadequate caloric intake can lead to weight loss, rather than weight gain.

**Correct Answer: A. Weight gain after TPN is expected due to adequate caloric intake and essential nutrient provision.**