## Core Concept
The comparison of protein content between cow's milk and human milk is crucial in understanding the nutritional differences between these two types of milk. Cow's milk and human milk have distinct compositions to meet the nutritional needs of their respective consumers, namely calves and human infants. The protein content in milk is an essential factor in supporting growth and development.

## Why the Correct Answer is Right
Cow's milk contains a higher concentration of protein compared to human milk. This is because calves, the target consumers of cow's milk, require a diet rich in protein to support their rapid growth and development. In contrast, human infants have a slower growth rate and different nutritional requirements. The protein in cow's milk is primarily casein, which forms a hard curd in the stomach, whereas human milk contains more whey proteins, which form a soft curd. This difference makes human milk easier to digest for infants.

## Why Each Wrong Option is Incorrect
- **Option A:** This option suggests that the protein content in cow's milk is lower than in human milk, which contradicts the established fact that cow's milk has a higher protein content.
- **Option B:** This option implies an equal protein content between cow's milk and human milk, which is not accurate based on the known compositions of these milks.
- **Option D:** This option indicates a significantly lower protein content in cow's milk compared to human milk, which is incorrect.

## Clinical Pearl / High-Yield Fact
A key point to remember is that the protein content in cow's milk is approximately 3.2 grams per 100 mL, while in human milk, it is about 0.9 grams per 100 mL. This significant difference necessitates adjustments when considering cow's milk as a substitute or supplement for human infants, to avoid overloading their systems with protein.

## Correct Answer: C.