## **Core Concept**
The question tests the knowledge of specialized microscopes used in cellular biology. It focuses on the type of microscope that allows for quantitative measurements of chemical constituents within cells. This involves understanding the capabilities of different microscopic techniques.

## **Why the Correct Answer is Right**
The correct answer, **C.**, refers to a **Microfluorometer** or more broadly, **Fluorescence Microscopy** when considering quantitative measurements. This technique enables the measurement of the chemical constituents of cells by using fluorescent probes that bind to specific molecules. The intensity of fluorescence can be quantitatively measured, providing information on the concentration of these molecules within the cell.

## **Why Each Wrong Option is Incorrect**
- **Option A:** This option is incorrect because, although it might refer to a type of microscopy, it does not specifically enable quantitative measurements of chemical constituents.
- **Option B:** This option is incorrect as it might refer to another specialized form of microscopy but does not directly relate to the quantitative analysis of cellular chemical constituents.
- **Option D:** This option is incorrect because it likely refers to another form of microscopy that does not specifically offer the capability for quantitative chemical measurements within cells.

## **Clinical Pearl / High-Yield Fact**
A key point to remember is that **Fluorescence microscopy** is widely used in research and diagnostics for its ability to specifically label and quantify molecules within cells. This technique is invaluable in fields like cancer research, immunology, and cell biology.

## **Correct Answer:** C. Microfluorometer.