**Core Concept**
The measurement of all proteins expressed in a cell or tissue is a crucial aspect of proteomics, which involves the study of the complete set of proteins produced or modified by an organism or system. This process is essential for understanding the complex interactions between proteins and their role in various diseases.

**Why the Correct Answer is Right**
The correct answer is related to the concept of proteomics, specifically the measurement of all proteins expressed in a cell or tissue. This can be achieved through techniques such as mass spectrometry, which allows for the identification and quantification of thousands of proteins in a single experiment. The process involves breaking down the proteins into smaller peptides, which are then analyzed using mass spectrometry to determine their mass-to-charge ratio and identify the corresponding proteins. This information can provide insights into protein function, regulation, and interactions, as well as help identify potential biomarkers for disease.

**Why Each Wrong Option is Incorrect**
**Option A:** This option is not relevant to the measurement of all proteins expressed in a cell or tissue.
**Option B:** This option is incorrect because it refers to a technique used for measuring specific proteins, not all proteins.
**Option C:** This option is not accurate because it describes a process used for analyzing the structure of proteins, not measuring all proteins expressed in a cell or tissue.

**Clinical Pearl / High-Yield Fact**
One important aspect of proteomics is the ability to identify biomarkers for disease, which can be used for early diagnosis and treatment. For example, proteomics has been used to identify biomarkers for cancer, such as prostate-specific antigen (PSA) for prostate cancer.

**Correct Answer: C. Proteomics**