**Core Concept:**

The question is testing the understanding of the nutritional requirements and potential deficiencies in infants fed on goat's milk as compared to human milk or cow's milk. Goat's milk differs from human milk and cow's milk in terms of protein, fat, and lactose composition, which can lead to certain nutritional deficiencies in infants.

**Why the Correct Answer is Right:**

Infants fed exclusively on goat's milk may develop a deficiency in vitamin D due to the low vitamin D content in goat's milk. Vitamin D is essential for calcium absorption and bone health in infants. The correct answer, option D, highlights the deficiency associated with goat's milk consumption.

**Why Each Wrong Option is Incorrect:**

Option A refers to cow's milk, which is not the correct answer as it is not the same as human milk or goat's milk. Option B mentions human milk, which is the correct answer as it is the optimal milk choice for infants due to its balanced composition. Option C refers to no milk consumption, which is also incorrect as infants need a proper diet for their growth and development.

**Clinical Pearl/High-Yield Fact:**

Human milk, cow's milk, and goat's milk have distinct nutritional profiles that can impact infant health. Infants should ideally consume human milk or cow's milk, which are more similar to human milk in composition and provide a balanced diet for infants, while goat's milk is not the optimal choice due to its lower vitamin D content.

**Correct Answer:** D. Infants fed exclusively on goat's milk may develop vitamin D deficiency.