## Core Concept
The question pertains to the characteristics of *Streptococcus*, a genus of Gram-positive bacteria. These bacteria are known for their role in various infections, ranging from mild to severe. Understanding their properties is crucial for diagnosis and treatment.

## Why the Correct Answer is Right
*Streptococcus* species are classified based on their hemolytic properties (alpha, beta, or gamma hemolysis) and Lancefield grouping (based on carbohydrate antigens on their cell walls). The correct answer, which is not provided, would relate to a specific characteristic not universally applicable to all *Streptococcus* species.

## Why Each Wrong Option is Incorrect
- **Option A:** Without the specifics, we can't directly address why an option is incorrect, but generally, if an option states a characteristic common to many *Streptococcus* species (like being Gram-positive, catalase-negative, or specific hemolytic patterns), it would be correct and not the answer.
- **Option B:** Similarly, this would depend on the statement, but if it's a feature shared among *Streptococcus* species, it wouldn't be the correct answer to "all are true except."
- **Option C:** This option, presumably, would also describe a common feature of *Streptococcus* and thus not be the exception.
- **Option D:** Given as the correct answer, it implies that this option describes a feature not universally true for all *Streptococcus* species.

## Clinical Pearl / High-Yield Fact
A key point to remember is that *Streptococcus pneumoniae* (a species within this genus) is known for its polysaccharide capsule, which is a major virulence factor. This is a critical clinical correlation because the capsule is the target for pneumococcal vaccines.

## Correct Answer: D.