**Core Concept**
The question tests the understanding of the different types of microscopes used in cellular biology and their applications. The correct answer is related to a type of microscope that allows not only the visualization of cell organelles but also the quantitative measurement of chemical constituents within cells.

**Why the Correct Answer is Right**
The correct answer is an Electron Microscope (EM). An Electron Microscope uses a beam of electrons to produce a high-resolution image of the specimen. This allows for the visualization of cell organelles at the nanoscale. Additionally, Electron Microscopes can be equipped with Energy-Dispersive Spectroscopy (EDS) or Electron Energy Loss Spectroscopy (EELS) to analyze the chemical composition of the specimen. This capability enables the quantitative measurement of chemical constituents within cells.

**Why Each Wrong Option is Incorrect**
* **Option A:** Light Microscope - While a Light Microscope can reveal cell organelles, it does not have the capability for quantitative measurement of chemical constituents.
* **Option B:** Fluorescence Microscope - A Fluorescence Microscope is used to visualize specific structures or molecules within cells, but it does not provide quantitative measurement of chemical constituents.
* **Option D:** Scanning Probe Microscope - A Scanning Probe Microscope can provide high-resolution images of cell surfaces and measure physical properties, but it is not typically used for quantitative measurement of chemical constituents within cells.

**Clinical Pearl / High-Yield Fact**
The Electron Microscope is a powerful tool in cellular biology, allowing researchers to visualize and analyze the structure and composition of cells at the nanoscale.

**Correct Answer:** C. Electron Microscope